Educational Wealth

Temprature of the earth

Abdullah 0 Article, Astronomy Wednesday, February 12, 2014

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<span style="font-size: large;">The Earth’s Tilt </span></h3>
<span style="font-size: large;">Some parts of the earth heated much more than others. To understand this we have to consider how the <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>earth</b></a> moves. The earth rotates (turns) on its axis, an imaginary line that connects the North and South Poles, once every twenty-four hours. This spinning motion makes the sun appear to move from east to west and causes day and night on earth. </span><br />
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<span style="font-size: large;">Rotation</span></h3>
<span style="font-size: large;"> Rotation is the normal motion (movement) of most space objects. Rotate means ‘spin’.

Stars spin, planets spin, moons spin and galaxies spin - even atoms spin.

Moons rotate around planets, and <a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank"><b>planets</b></a> rotate around stars. The Earth rotates once every 23.93 hours. This is called its rotation period.

We do not feel the Earth’s rotation - that it is hurtling around the Sun, while the Sun whizzes around the galaxy - because we are moving with it.

Things rotate because they have kinetic (movement) energy. </span><br />
<span style="font-size: large;">They cannot fly away because they are held in place by gravity, and the only place they can go is round.

The fastest rotating planet is Saturn, which turns right around once every 10.23 hours.

The slowest rotating planet is Venus, which takes 243.01 days to turn round. </span><br />
<span style="font-size: large;"> The Sun takes 25.4 days to rotate, but since the Earth is going around it too, it seems to take 27.27 days.

The fastest spinning objects in the Universe are neutron stars - these can rotate 500 times in just one second. Rotating galaxies are just part of the spinning, moving universe.

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Rotation in universe

The sun is approximately 150 000 000 kilometres (93 000 000 miles) from earth. </span><br />
<span style="font-size: large;">The earth revolves (goes around) the sun once every year. In 365 days the earth travels a distance of 958 million kilometres (595 million miles) around the sun. This path is called the earth's orbit. The tilt of the earth's axis and the earth's revolution around the sun cause the change in seasons.</span><br />
<span style="font-size: large;"> How summer forms

For half the year, the Northern Hemisphere is tilted toward the sun causing summer.
How winter forms

For other half of the year, the Northern Hemisphere is tilted away from the sun. That's when we have winter. The equator receives direct sunlight all year round.

The highest temperature ever recorded on earth was 58° C (136° F.) at Al Azizyah, Libya and that the lowest ever recorded was-88° C (-127° F) at Vostok in Antarctica.These are extremes. </span><br />
<span style="font-size: large;">The average surface temperature on earth is 14° C (57° F).

In order to take temperatures, a thermometer is used to record temperature changes. Mercury is a metal that is used in this instrument. Metals expand when they are heated and contract when the temperature drops. The mercury is contained in a bulb at the end of a long narrow glass tube. </span><br />
<span style="font-size: large;">When the temperature rises, the mercury expands in the bulb and is pushed up the tube. A scale is marked on the thermometer showing the degrees of temperature rise. The two most common temperature scales used on thermometers are Celsius and Fahrenheit. At very low temperatures alcohol, not mercury, is used because it has a lower freezing point. </span><br />
<span style="font-size: large;"> If you live in a climate where temperatures are bitter cold in winter, you can understand why people wait in anticipation for the first sign of warm weather. In such climates, the weather is often a daily topic of conversation. But what would it be like to live in a hot, sultry desert, or in the jungles of <a href="http://educational-wealth.blogspot.com/2014/03/antarticaafrica-worlds-largest-continent.html" target="_blank"><b>Africa</b></a>, or perhaps far north in the Arctic regions. </span><br />
<span style="font-size: large;">The temperature affects our moods, our choice of clothing, our jobs and our overall lifestyle.

Over the past while there has been an enormous amount of talk with relation to our environment and, more specifically, "The Greenhouse Effect". You may be somewhat puzzled as to what this "Greenhouse Effect" actually is. To increase your awareness and knowledge read the information that follows.

As heat from the sun enters our atmosphere a certain percentage is reflected back into space mostly by the clouds.</span><br />
<span style="font-size: large;"> But close to 50% of the sunlight reaches the earth's surface to heat the land and waters. Heat then comes from the land and waters to warm the atmosphere. The atmosphere absorbs the heat and it is prevented from passing back into space because of the buildup of carbon dioxide and other gases such as chlorofluorocarbons (CFC's) and methane. </span><br />
<span style="font-size: large;">These gases act like the glass in a greenhouse. A greenhouse is a building made basically from glass where plants can be grown all year round because the greenhouse allows the sunlight in but prevents the heat from escaping. Likewise, the sun's heat in our atmosphere is trapped by gases.
How smog produces

The carbon dioxide and other gases are the direct result of human activities. Exhaust from cars and other modes of transportation, smog pouring from the smokestacks of factories, the gases released from residential and commercial heating - all contribute to this deplorable problem. </span><br />
<span style="font-size: large;">The excessive chopping of trees also aggravates the issue because trees absorb a lot of carbon dioxide.

Scientists warn us about this global warming, as it's referred to. Our planet is gradually "heating" up. If it continues it can eventually lead to widespread drought and the melting of the polar <a href="http://educational-wealth.blogspot.com/2014/03/worlds-glaciers-and-ice-ages.html" target="_blank">ice</a> cap could cause coastal flooding. Generally speaking most authorities believe that it is essential that we all work together to rectify this problem. </span><br />
<span style="font-size: large;">The CFC's are also being blamed for the deterioration of the ozone layer. The ozone layer is a layer of gas called "ozone" that protects the Earth from nearly 90% of the sun's ultraviolet rays. In the late 1970's some scientists found a hole in the ozone layer over the Antarctica region. </span><br />
<span style="font-size: large;">Since then, the problem has gotten progressive worse. Exposure to an overabundance of ultraviolet rays can leac to all kinds of problems - from severe <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>sun</b></a>burn to skin cancer. In 19th centurey a treaty was signed by forty countries to take action against CFC' One common source of CFC's is the use of aerosol spray cans. </span><br />
<span style="font-size: large;"> We all have a responsibility to clean up our environment. In the garbage cans below write six ways you can help with these environmental issues.

On a T-shirt shape create an illustration and slogan which will encourage people to become more conscious of environme issues, (i.e. banning aerosol cans, plastics, recycling, the greenhouse effect, the ozone crisis, etc.) "Whether" we save our planet or not is up to us. </span></div>

Temprature of the earth

The Earth’s Tilt Some parts of the earth heated much more than others. To understand this we have to consider how the earth moves. The ...

Space telescopes and Crafts

Abdullah 0 Article, Astronomy Thursday, February 06, 2014

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<span style="font-size: large;">Space telescopes </span></h3>
<span style="font-size: large;">Space telescopes are launched as satellites so we can study the Universe without interference from Earth’s atmosphere. </span><br />
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<tr><td class="tr-caption" style="text-align: center;">Telescope</td></tr>
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<span style="font-size: large;">First space telescope </span></h3>
<span style="font-size: large;">The first space telescope was Copernicus, sent up in 1972.

The most famous is the <a href="http://educational-wealth.blogspot.com/2014/02/edwin-hubble-galilio.html" target="_blank"><b>Hubble space telescope</b>,</a> launchttp://educational-wealth.blogspot.com/2014/02/what-are-planets.htmlhed from a space shuttle in 1990.

Different space telescopes study all the different forms of radiation that make up the electromagnetic spectrum .</span><br />
<span style="font-size: large;"> </span><span style="font-size: large;"><b>Hubble space telescope</b> </span><br />
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<span style="font-size: large;"><span style="font-size: large;"> In 1994 the crew of Discovery mended the Hubble space telescope in <b>orbit</b>.

The entire centre section of the orbiter is a cargo bay which can be opened in space so satellites can be placed in orbit</span> </span></div>
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<span style="font-size: large;">Helios telescope </span></h3>
<span style="font-size: large;"> Helios 
was one of many space telescopes studying the Sun.

X-rays can only be picked up by space telescopes such as the Einstein, 
ROSAT and XTE satellites.

Gamma rays can only be picked up by space telescopes like the Compton 
Gamma-Ray Observatory.

The Hubble space telescope’s main mirror was faulty when it was 
launched, but a replacement was fitted by shuttle astronauts in 1994. </span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">Satellites </span></h3>
<span style="font-size: large;"> A One of the many hundreds of satellites now in Earth’s orbit.

Satellites are objects that orbit planets and other space objects. Moons are natural satellites. Spacecraft sent up to orbit the Earth and the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> are artificial satellites.

The first artificial satellite was Sputnik 1, launched on 4 October 1957.</span><br />
<span style="font-size: large;"> About 100 artificial satellites are now launched every year.

A few of them are space telescopes.
<a href="http://educational-wealth.blogspot.com/2014/01/ways-of-information.html" target="_blank">Communications</a> satellites beam everything from <a href="http://educational-wealth.blogspot.com/2014/01/ways-of-information.html" target="_blank"><b>TV</b></a>

pictures to <b><a href="http://educational-wealth.blogspot.com/2014/01/ways-of-information.html" target="_blank">telephone</a> </b>calls around the world.</span><br />
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<b><span style="font-size: large;"> </span><span style="font-size: large;">Observation satellites</span></b></h3>
<span style="font-size: large;"> Observation satellites scan the Earth and are used for purposes such as scientific research, weather forecasting and spying. </span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">Navigation satellites </span></h3>
<span style="font-size: large;">Navigation satellites such as the Global Positioning System (GPS) are used by people such as airline pilots to work out exactly where they are. </span><br />
<span style="font-size: large;"><span style="font-size: large;"> <b>Geostationary orbit</b></span> </span><br />
<span style="font-size: large;">Satellites are launched at a particular speed and trajectory (path) to place them in just the right orbit. </span><br />
<span style="font-size: large;"> The lower a satellite’s <b>orbit</b>, the faster it must fly to avoid falling back to Earth. Most satellites fly in low orbits, 500 km above the Earth.

A geostationary orbit is 35,786 km up. Satellites in geostationary orbit over the Equator always stay in exactly the same place above the Earth. </span><br />
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<span style="font-size: large;">COBE satellite </span></h3>
<span style="font-size: large;">The COBE satellite picks up microwave radiation which may be left over from the <a href="http://educational-wealth.blogspot.com/2014/03/galaxies.html" target="_blank"><b>Big Bang</b></a>. </span><br />
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<span style="font-size: large;">IRAS satellite </span></h3>
<span style="font-size: large;">The IRAS satellite studied infrared radiation from objects as small as space dust.

Space telescopes that study ultraviolet rays from the <b>stars</b> included the International Ultraviolet Explorer (IUE), launched in 1978.</span><br />
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<span style="font-size: large;"><span style="font-size: large;"> Polar orbiting satellites</span> </span></h3>
<span style="font-size: large;"> Polar orbiting satellites circle the Earth from pole to pole about 850 km up, covering a different strip of the Earth’s surface on each orbit. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">Communications satellites</span> </span></h3>
<span style="font-size: large;"> Communications satellites act as relay stations, receiving signals from one location and transmitting them to another. </span><br />
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<span style="font-size: large;">Spacecraft </span></h3>
<span style="font-size: large;"> There are three kinds of spacecraft -</span><br />
<span style="font-size: large;"> 1-Artificial satellites</span><br />
<span style="font-size: large;">2- unmanned probes </span><br />
<span style="font-size: large;">3-Manned spacecraft. </span><br />
<span style="font-size: large;">Spacecraft have double hulls  to protect against other space objects that crash into them.

Manned spacecraft must also protect the crew from heat and other dangerous effects of launch and landing.

Spacecraft windows have filters to protect astronauts from the Sun’s dangerous ultraviolet rays. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">Flying saucers</span> </span></h3>
<span style="font-size: large;"> Supposed alien spacecraft are sometimes called ‘flying saucers’. Modern science-fiction portrays them as more like this.</span><br />
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<span style="font-size: large;">Space travel

Radiators</span></h3>
<span style="font-size: large;"> Space travel

Radiators on the outside of the spacecraft lose heat, to stop the crew’s body <a href="http://educational-wealth.blogspot.com/2014/02/temprature-of-earth.html" target="_blank"><b>temperature</b></a>s overheating the craft. </span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">Manned spacecraft</span></h3>
<span style="font-size: large;"> Manned spacecraft have life-support systems that provide oxygen to breathe, usually mixed with nitrogen (as in ordinary air). </span><br />
<span style="font-size: large;">Charcoal filters out smells.

The US space shuttle, the first reusable spacecraft, has made manned space flights out into Earth’s orbit and back almost a matter of routine.

The carbon dioxide that crews breathe out is absorbed by pellets of lithium hydroxide.</span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">Spacecraft toilets</span></h3>
<span style="font-size: large;">Spacecraft toilets have to get rid of waste in low gravity conditions. Astronauts have to sit on a device which sucks away the waste.</span><br />
<span style="font-size: large;"> Solid waste is dried and dumped in space, but the water is saved.

To wash, astronauts have a waterproof shower which sprays them with jets of water from all sides and also sucks away all the waste water. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">Weightlessness of space</span> </span></h3>
<span style="font-size: large;">The weightlessness of space means that most astronauts sleep floating in the air, held in place by a few straps. </span><br />
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<span style="font-size: large;"> Rockets </span></h3>
<span style="font-size: large;"> Rockets provide the huge thrust needed to beat the pull of Earths gravity and launch a spacecraft into space.

The space shuttle uses a huge fuel tank and two booster rockets to launch.</span><br />
<span style="font-size: large;"> After launch the booster rockets fall away from the shuttle. </span><br />
<span style="font-size: large;">The shuttle uses its own power to complete its mission before returning to Earth.

Rockets burn propellant , to produce hot gases that drive the rocket upwards.</span><br />
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<span style="font-size: large;">Rocket's fuel </span></h3>
<span style="font-size: large;">Rocket propellant comes in two parts -a solid or liquid fuel, and an oxidizer. </span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">Solid fuel</span></h3>
<span style="font-size: large;"> Solid fuel is a rubbery substance that contains hydrogen, and it is usually used in additional, booster rockets. </span><br />
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<span style="font-size: large;"><span style="font-size: large;"> Liquid fuel</span> </span></h3>
<span style="font-size: large;"> Liquid fuel is usually liquid hydrogen, and it is typically used on big rockets.

There is no oxygen in space, and the oxidizer supplies the oxygen needed to burn fuel.</span><br />
<span style="font-size: large;"> It is usually liquid oxygen (called ‘lox’ for short). </span><br />
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<span style="font-size: large;"><b>First liquid fuel rocket</b> </span></h3>
<span style="font-size: large;">The first rockets were made 1000 years ago, in China.

Robert Goddard launched the very first liquid-fuel rocket in 1926.

The German V2 war rocket, designed by Werner von Braun, was the first rocket capable of reaching space.</span><br />
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<b><span style="font-size: large;">Space shuttle </span></b></h3>
<span style="font-size: large;"> Unlike other spacecraft, the space shuttle can land like an aeroplane ready for another mission. But even the shuttle has to be launched into space on the back of huge rockets. These soon fall back to Earth, where they are collected for reuse.

The most powerful rocket ever was the Saturn 5 that sent astronauts to the Moon. </span><br />
<span style="font-size: large;"> The space shuttle is a reusable spacecraft, made up of a 37.2-m-long 
orbiter, two big Solid Rocket Boosters (SRBs), three main engines and a 
tank.

The shuttle orbiter is launched into space upright on SRBs, which fall 
away to be collected for reuse. </span><br />
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<span style="font-size: large;">Orbital velocity</span></h3>
<span style="font-size: large;">The biggest problem when launching a spacecraft is overcoming the pull of Earth’s gravity.

To escape Earth’s gravity, a spacecraft must be launched at a particular velocity .</span><br />
<span style="font-size: large;"> The minimum velocity needed for a spacecraft to combat gravity and stay in orbit around the Earth is called the orbital velocity. </span><br />
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<span style="font-size: large;">Escape velocity </span></h3>
<span style="font-size: large;">When a spacecraft reaches 140 percent of the orbital velocity, it is going fast enough to break free of Earth’s gravity. </span><br />
<span style="font-size: large;">This is called the escape velocity. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">Launch vehicles</span> </span></h3>
<span style="font-size: large;">The thrust (push) that launches a spacecraft comes from powerful rockets called launch vehicles.

Launch vehicles are divided into sections called stages, which fall away as their task is done. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">First stage of Launch vehicles</span> </span></h3>
<span style="font-size: large;">The first stage lifts everything off the ground, so its thrust must be greater than the weight of launch vehicle plus spacecraft.</span><br />
<span style="font-size: large;"> It falls away a few minutes after take off. </span><br />
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<span style="font-size: large;"><span style="font-size: large;">Second stage of Launch vehicles</span></span></h3>
<span style="font-size: large;"> A second stage is then needed to accelerate the spacecraft towards escape velocity.

After the launch stages fall away, the spacecraft’s own, less powerful, rocket motors start.

To stay in orbit 200 km up, a spacecraft

has to fly at over 8 km per second. </span><br />
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<span style="font-size: large;">Wings and space craft </span></h3>
<span style="font-size: large;">A spacecraft cannot use wings to lift it off the ground, as wings only work in the lower atmosphere. Instead, launch rockets must develop a big enough thrust to power them straight upwards, overcoming gravity with a mighty blast of heat.  </span><br />
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<span style="font-size: large;">Landing of Orbitars </span></h3>
<span style="font-size: large;">When the mission is over the orbiter lands like a glider.

The orbiter can go as high as a near-Earth orbit, some 300 km above the Earth.

The maximum crew is eight, and a basic mission is seven days, during which the crew work in shirtsleeves.

Orbiter toilets use flowing air to suck away waste.

The orbiter can carry a 25,000 kg-load in its cargo bay. </span><br />
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<span style="font-size: large;">First four orbiters </span></h3>
<span style="font-size: large;"> The first four orbiters were named after old sailing ships - Columbia, Challenger, Discovery and Atlantis. </span><br />
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<span style="font-size: large;">Engines of orbitars </span></h3>
<span style="font-size: large;">The three main engines are used only for lift-off.</span><br />
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<span style="font-size: large;">Orbital Manoeuvring System (OMS)</span></h3>
<span style="font-size: large;"> In space, the small Orbital Manoeuvring System (OMS) engines take over.</span><br />
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<span style="font-size: large;"> </span><span style="font-size: large;">The Reaction Control System (RCS) </span></h3>
<span style="font-size: large;"> The Reaction Control System (RCS) makes small adjustments to the orbiter’s position.

In future, faster space planes may take over from shuttles, so that humans can visit other planets. </span><br />
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<span style="font-size: large;">Tragedy with shuttle in 1986 </span></h3>
<span style="font-size: large;">The 2003 shuttle programme was brought to an untimely end when the Columbia exploded killing all seven crew members. This tragedy echoed the ill-fated Challenger programme of 1986.</span><br />
<span style="font-size: large;">. </span><br />
<span style="font-size: large;">Space probes Voyager 2 used Saturn’s gravity to fly on to Uranus and <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Neptune</b></a>.

Space probes are automatic, computer-controlled unmanned spacecraft sent to explore space.

The first successful planetary probe was the USA’s Mariner 2, which flew past <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Venus</b></a> in 1962.  Mariner 10 reached Mercury in 1974. </span><br />
<span style="font-size: large;">Vikings 1 and 2 landed on  <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Mars</b></a> in 1976.  Voyager 2 has flown over six billion km and is heading out of the Solar System after passing close to Jupiter (1979), Saturn (1980), Uranus (1986) and Neptune (1989).

Most probes are ‘fly-bys’ which spend just a few days passing their target and beaming back data to <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a>. </span><br />
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<span style="font-size: large;"> Slingshot</span></h3>
<span style="font-size: large;">To save fuel on journeys to distant planets, space probes may use a nearby planet’s gravity to catapult them on their way.</span><br />
<span style="font-size: large;"> This is called a slingshot.</span><br />
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<span style="font-size: large;">Space probes </span></h3>
<span style="font-size: large;"> In the first ten years of the 21st century, more than 50 space probes will be sent off to visit <b>planets</b>, asteroids and comets, as well as to observe the Moon and the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a>.

Space probes will bring back samples from Mars, comets and asteroids early in the 21 st century.</span><br />
<span style="font-size: large;">Probes are equipped with a wealth of equipment for recording data and beaming it back to Earth.</span><br />
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<span style="font-size: large;"><span style="font-size: large;">Terrestrial Planet Finder (TPF)</span> </span></h3>
<span style="font-size: large;"> Terrestrial Planet Finder (TPF) may be used to detect planets circling nearby stars in 2009. </span><br />
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<span style="font-size: large;">Voyagers 1 and 2 </span></h3>
<span style="font-size: large;">The Voyagers are a pair of unmanned US space probes, launched to explore the outer planets.

Voyager 1 was launched on 5 September 1977.</span><br />
<span style="font-size: large;"> It flew past Jupiter in March 1979 and Saturn in November 1980, then headed onwards.Jupiter's orange moon. Voyager 2 discovered sulphur volcanoes on this moon, in 1979.

on a curved path that will take it out of the Solar System altogether.

Voyager 2 travels more slowly.</span><br />
<span style="font-size: large;"> Although launched two weeks earlier than Voyager 1, it did not reach Jupiter until July 1979 and Saturn until August 1981.

The Voyagers used the ‘slingshot’ of Jupiter’s gravity  to hurl them on towards <a href="http://educational-wealth.blogspot.com/2014/02/very-beautiful-saturn-rings.html" target="_blank"><b>Saturn</b></a>.

While Voyager 1 headed out of the Solar System, Voyager 2 flew past Uranus in January 1986 and <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Neptune</b></a> on 24 August 1989. </span><br />
<span style="font-size: large;">It took the first close-up photographs of the two <a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank">planets</a>.

The Voyagers revealed volcanoes on Io, one of Jupiter’s Galilean moons.

Voyager 2 found ten unknown moons around <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Uranus</b></a>.

Voyager 2 found six unknown <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>moon</b></a>s and three rings around Neptune.

Voyager 2 reached <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Neptune</b></a> in 1989, revealing a wealth of new information about this distant planet.

Voyager 2 will beam back data until 2020 as it travels beyond the edges of the Solar System. </span></div>

Space telescopes and Crafts

Space telescopes Space telescopes are launched as satellites so we can study the Universe without interference from Earth’s atmosphere. ...

The Moons

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<h3 style="text-align: left;">
<span style="font-size: large;">The Moons</span></h3>
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<span style="font-size: large;">Moons are the natural satellites of planets. Most are small <a href="http://educational-wealth.blogspot.com/2014/02/rocks-of-earth.html" target="_blank"><b>rock</b></a> globes that continually orbit the parent planet, held in place by the planet’s gravity.

There are 65 known moons in the Solar System.

Every planet in the Solar System has a moon, apart from Mercury and <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Venus</b></a>, the nearest planets to the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a>.

New moons are frequently discovered, as space probes such as the Voyagers reach distant planets. </span><br />
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<tr><td class="tr-caption" style="text-align: center;">The Moon</td></tr>
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<span style="font-size: large;"></span><span style="font-size: large;">Moons are the natural satellites of planets. Most are small <a href="http://educational-wealth.blogspot.com/2014/02/rocks-of-earth.html" target="_blank"><b>rock</b></a> globes that continually orbit the parent planet, held in place by the planet’s gravity.

There are 65 known moons in the Solar System.

New moons are frequently discovered, as space probes such as the Voyagers reach distant planets. </span></div>
<span style="font-size: large;">Three moons have atmospheres - <a href="http://educational-wealth.blogspot.com/2014/02/very-beautiful-saturn-rings.html" target="_blank"><b>Saturn</b></a>’s moon Titan, Jupiter’s Io, and <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Neptune</b></a>’s Triton.

The Moon is 384,400 km from the Earth and about 25 percent of Earth’s size. </span><br />
<span style="font-size: large;">The Moon orbits the Earth once every month, with each orbit taking 27.3 days. It spins round once on its axis every 720 hours.  The Moon is the only other world that humans have ever set foot on. Because the Moon has no atmosphere or wind, the footprints planted in its dusty surface in 1969 by the Apollo astronauts are still there today, perfectly preserved. </span><br />
<span style="font-size: large;">The Moon is the brightest object in the night sky, but it does not give out any light itself. It shines only because its light-coloured surface reflects sunlight.

Only the side of the Moon lit by the

<a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> is bright enough to see.

And because we see more of this side each month as the Moon orbits the Earth, and then less again, the Moon seems to change shape. </span><br />
<span style="font-size: large;"> These changes are called the Moon’s phases. During the first half of each monthly

cycle, the Moon waxes (grows) from a crescent-shaped new moon to a full moon. During the second half, it wanes (dwindles) back to a crescent-shaped old moon.

A lunar month is the time between one full moon and the next. </span><br />
<span style="font-size: large;">This is slightly longer than the time the Moon takes to orbit the Earth because the Earth is also moving.

The Moon has no atmosphere and its surface is simply grey dust, pitted with craters created by meteorites smashing into it early in its history.

<a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank"><b>Planets</b></a>

On the Moon’s surface are large, dark patches called seas - because that is what people once believed they were. </span><br />
<span style="font-size: large;">They are, in fact, lava flows from ancient volcanoes.

One side of the Moon is always turned away from us and is called its dark side. This is because the Moon spins round on its axis at exactly the same speed that it orbits the Earth.

Unlike the Earth’s surface, which changes by the hour, the Moon’s dusty, crater-pitted surface has remained much the same for billions of years.</span><br />
<span style="font-size: large;"> The only change happens when a meteorite smashes into it and creates a new crater.

The Moons gravity is 17 percent of the earths, so astronauts in space suits canjump 4 m high!

Laser measurements showed that, on average, the Moon is 376,275 km away from the Earth. </span><br />
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<span style="font-size: large;">Gravity on the Moon is so weak that astronauts can leap high into the air wearing their heavy space suits.
<a href="http://educational-wealth.blogspot.com/2014/02/temprature-of-earth.html" target="_blank"><b>Temperatures </b></a>reach 117°C at midday on the Moon, but plunge to -162°C at night.
Moon landing

The first Moon landing was by the unmanned Soviet probe Lunar 9, which touched down on the Moons surface in 1966. </span></div>
<span style="font-size: large;"> The first men to orbit the Moon were the astronauts on board the US Apollo 8 in 1968.

On 20 July 1969 the American astronauts Neil Armstrong and Edwin (Buzz) Aldrin became the first men ever to walk on the Moon. </span><br />
<span style="font-size: large;"> When Neil Armstrong stepped on to the Moon for the first time, he said these famous words: ‘That’s one small step for a man; one giant leap for mankind.’

Twelve men have landed on the Moon between 1969 and 1972.

The Apollo 13 mission to the Moon suffered near tragedy when an explosion ripped through the service module. </span><br />
<span style="font-size: large;">The crew managed to return to Earth using the command module.

The Moon astronauts brought back 380 kg of Moon rock.

A mirror was left on the Moon’s surface to reflect a laser beam which measured the Moon’s distance from <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a> with amazing accuracy.

</span></div>

The Moons

The Moons Moons are the natural satellites of planets. Most are small rock globes that continually orbit the parent planet, held in pl...

Asteroids and Comets

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<span style="font-size: large;">Asteroids </span><br />
<span style="font-size: large;">Asteroids are lumps of <a href="http://educational-wealth.blogspot.com/2014/02/rocks-of-earth.html" target="_blank"><b>rock</b></a> that orbit the Sun. They are sometimes called the minor <a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank"><b>planets</b></a>.

Most asteroids - more than half a million - orbit the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> in the Asteroid Belt, between Mars and Jupiter.

Every 50 million years, the <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b> </a>is hit by an asteroid measuring over 10 km across.

Most asteroids are in the Asteroid Belt, which lies between <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Mars</b></a> and Jupiter. </span><br />
<span style="font-size: large;"> Some distant asteroids are made of ice and orbit the Sun beyond Neptune.

A few asteroids come near the Earth. These are called Near Earth Objects (NEOs).

The first asteroid to be discovered was Ceres in 1801. It was detected by Giuseppi Piazzi, one of the Celestial Police whose mission was to find a ‘missing’ planet.

Ceres is the biggest asteroid - 940 km across, and 0.0002 percent of the size of the Earth.</span><br />
<span style="font-size: large;"> The Galileo space probe took close-up pictures of the asteroids Ida and Gaspra in 1991 and 1993.

There are half a million or so asteroids bigger than 1 km across.

More than 200 asteroids are over 100 km across.

The Trojan asteroids are groups of asteroids that follow the same orbit as Jupiter. Many are named after warriors in the ancient Greek tales of the Trojan wars.</span><br />
<b><span style="font-size: large;"> Comets</span></b><br />
<span style="font-size: large;"> Comets are bright objects with long tails, which we sometimes see streaking across the night sky.

They may look spectacular, but a comet is just a dirty ball of <a href="http://educational-wealth.blogspot.com/2014/03/worlds-glaciers-and-ice-ages.html" target="_blank">ice</a> a few kilometres across.

Many comets orbit the Sun, but their orbits are very long and they spend most of the time in the far reaches of the Solar System.

A comet’s tail is made as it nears the Sun and begins to melt.</span><br />
<span style="font-size: large;"> A vast plume of gas millions of kilometres across is blown out behind by the solar wind. The tail is what you see, shining as the sunlight catches it.

Comets called periodics appear at regular intervals.

Some comets reach speeds of two million km/h as they near the Sun.

Far away from the Sun, comets slow down to 1000 km/h or so - that is why they stay away for so long.</span><br />
<span style="font-size: large;"> The visit of the comet Hale-Bopp in 1997 gave the brightest view of a comet since 1811, visible even from brightly lit cities.

The Shoemaker-Levy 9 comet smashed into Jupiter in July 1994, with the biggest crash .</span><br />
<span style="font-size: large;"> The tail of a comet always

ever witnessed.

The most famous comet of all

is Hailey’s comet Comet Kahoutek streaks through the night sky. </span><br />
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<span style="font-size: large;">Hailey s comet </span></h3>
<span style="font-size: large;"> Hailey’s comet is named after the British scientist Edmund Hailey (1656-1742).

Hailey predicted that this particular comet would return in 1758, 16 years after his death. It was the first time a comet’s arrival had been predicted.

Hailey’s comet orbits the Sun every 76 years.</span><br />
<span style="font-size: large;"> Its orbit loops between Mercury and Venus, and stretches out beyond Neptune. </span><br />
<span style="font-size: large;"> Its next visit will be in 2062.

The Chinese described a visit of Hailey’s comet as long ago as 240bc.When Hailey’s cometwas seen in 1837,

Chinese astronomers wrote that its head was as bright as <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Venus</b></a> and its tail stretched right through the sky.

Harold, King of England, saw the comet in 1066. </span><br />
<span style="font-size: large;">When he was defeated by William the Conqueror a few months later, people took the comet’s visit as an evil omen.

Hailey’s comet was embroidered on the Bayeux tapestry, which shows Harold’s defeat by William.

</span></div>

Asteroids and Comets

Asteroids Asteroids are lumps of rock that orbit the Sun. They are sometimes called the minor planets . Most asteroids - more than half...

Sun and it’s rays

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<span style="font-size: large;">The Sun</span></h2>
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<tr><td class="tr-caption" style="text-align: center;">The sun</td></tr>
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<span style="font-size: large;"> </span><span style="font-size: large;">Medium-sized star</span></h3>
<span style="font-size: large;">The Sun is a medium-sized star measuring 1,392,000 km across.The Sun weighs 2000 trillion tonnes - about 300,000 times as much as the Earth - even though it is made almost entirely of hydrogen and helium, the lightest gases in the Universe.

The Sun’s interior is heated by nuclear reactions to temperatures of 15 million °C. </span><br />
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<span style="font-size: large;">P<span style="font-size: large;">hotosphere</span> </span></h3>
<span style="font-size: large;">The visible surface layer of the Sun is called the photosphere. This sea of boiling gas sends out the light and heat we see and feel on <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a>.

Suns surface is a turbulent mass offlames and tongues of hot gases - very different from the even, yellowish ball we see from Earth. </span><br />
<h3>
<span style="font-size: large;"><b><span style="font-size: large;">Chromosphere</span></b> </span></h3>
<span style="font-size: large;"> Above the photosphere is the chromosphere, a thin layer through which dart flames called spicules, making the chromosphere look like a flaming forest.

Above the chromosphere is the Sun’s halo-like corona.</span><br />
<span style="font-size: large;"> The heat from the Sun’s interior

erupts on the surface in patches called granules, and gigantic, flame- like tongues of hot gases called solar prominences.The Sun gets hot because it is so big that the pressure in its core is tremendous - enough to force the nuclei of hydrogen atoms to fuse (join together) to make helium atoms. </span><br />
<span style="font-size: large;">This nuclear fusion reaction is like a gigantic atom bomb and it releases huge amounts of heat.</span><br />
<span style="font-size: large;"> Halfway out from its centre to its surface, the Sun is about as dense as water. Two-thirds of the way out, it is as dense as air.

prominence sunspot

The nuclear fusion reactions in the

Suns core send out billions of light photons every minute (see light) - but they take 10 million years to reach its surface. </span><br />
<span style="font-size: large;">The temperature of the Sun’s surface is 6000°C. Each centimetre burns with the brightness of 250,000 candles!

The Sun is made mostly of hydrogen and helium, and has many layers. It has a core, where most heat is made, then a number of layers building to the flaming chromosphere on its surface.

Sunspots

Sunspots are dark spots on the Sun’s photosphere (surface), 2000°C cooler than the rest of the surface. </span><br />
<span style="font-size: large;"> The dark centre of a sunspot is the umbra, the coolest bit of a sunspot. Around it is the lighter penumbra.

Sunspots appear in groups which seem to move across the Sun over two weeks, as the Sun rotates.

Individual sunspots last less than a day.

A Infrared photographs reveal the dark sunspots that appear on the surface of the Sun. </span><br />
<span style="font-size: large;"> The number of sunspots reaches a maximum every 11 years. This is called the solar or sunspot cycle.

The next sunspot maximum will be in the year 2002.

Earth’s weather may be warmer and stormier when sunspots are at their maximum.</span><br />
<span style="font-size: large;"> Long-term sunspot cycles are 76 and

180 years, and are almost like the Sun breathing in and out.

Observations of the Sun by satellites such as Nimbus-7 showed that less heat reaches the Earth from the Sun when sunspots are at a minimum.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Solar eruption</span></h3>
<span style="font-size: large;">Solar eruptions takes place on the Sun’s surface.  They flare up in just a few minutes, then take more than half an hour to die away again.

Solar flares reach temperatures of 10 million °C and have the energy of a million atom bombs.

Solar flares not only send out heat and radiation, but also streams of charged particles. </span><br />
<span style="font-size: large;"> The solar wind is the stream of charged particles that shoots out from the Sun in all directions at speeds of over a million km/h. It reaches the Earth in 21 hours, but also blows far throughout the Solar System.

Every second the solar wind carries away over a million tonnes of charged particles from the Sun.

Earth is shielded from the lethal effects of the solar wind by its magnetic field .

Solar prominences are gigantic, flame-like tongues of hot hydrogen that sometimes spout out from the Sun.Solar prominences reach <a href="http://educational-wealth.blogspot.com/2014/02/temprature-of-earth.html" target="_blank"><b>temperature</b></a>s of 10,000°C. </span><br />
<span style="font-size: large;"> Coronal mass ejections are gigantic eruptions of charged particles from the Sun, creating gusts in the solar wind which set off magnetic storms on Earth.

Magnetic storms are massive hails of charged particles that hit the Earth every few years or so, setting the atmosphere buzzing with electricity. Solar prominences can stretch for many thousands of kilometres. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Solar changes </span></h3>
<span style="font-size: large;"> The Sun is about five billion years old and halfway through its life - as a medium-sized star it will probably live for around ten billion years.

Over the next few billion years the Sun will brighten and swell until it is twice as bright and 50 percent bigger.

The Sun will end as a

white dwarf .</span><br />
<span style="font-size: large;">The Sun seems to burn so steadily that we take for

granted that it will be equally bright and warm all the time. In the short term, however, its brightness does seem to vary very slightly all the time, and over the next 5 billion years it will probably burn more and more ferociously.

In five billion years, the

Sun’s hydrogen fuel will have burned out, and its core will start to shrink. </span><br />
<span style="font-size: large;"> As its core shrinks, the

rest of the Sun will swell up with gases and its surface will become cooler and redder. It will be a red giant star.

The Earth will have been burned to a cinder long before the Sun is big enough to swallow it up completely.

The Sun’s brightness varies, but it was unusually dim and had no sunspots between 1645 and 1715 - this period is called the Maunder minimum.</span><br />
<span style="font-size: large;"> The Earth suffered the Little<a href="http://educational-wealth.blogspot.com/2014/03/worlds-glaciers-and-ice-ages.html" target="_blank"><b> Ice Age </b></a>at this time.

More of the chemical carbon-14 is made on Earth when the Sun is

more active. The carbon-14 is taken into trees, which means scientists can work out changes in solar activity in the past by measuring carbon-14 in old wood.</span><br />
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<span style="font-size: large;"> Eclipses</span></h3>
<span style="font-size: large;"> An eclipse is when the light from a star such as the Sun is temporarily blocked off by another space object.

A lunar eclipse is when the Moon travels behind the Earth, and into the Earths shadow Earth is between the Moon and the Sun.

Lunar eclipses happen once or twice every year and last only a few hours.

In a total lunar eclipse, the Moon turns rust-red.

There will be a total lunar eclipse on'3 March 2007 and 28 August 2007. </span><br />
<span style="font-size: large;">A solar eclipse</span><br />
<span style="font-size: large;">A solar eclipse is when the Moon comes between the Sun and the Earth, casting a shadow a few kilometres wide on to the Earth’s surface.

A During a total solar eclipse of the Sun, the Moon blocks out everything but the Sun s corona.

In a total eclipse of

the Sun, the Moon passes directly in front of the Sun, completely covering it so that only its corona can be seen . </span><br />
<span style="font-size: large;">There are one or two

solar eclipses every year, but they are visible only from a narrow strip of the world.

There will be a total solar eclipse on 29 March 2006 and 1 August 2008.

Solar eclipses are possible because the Moon is 400 times smaller than the Sun, and is also 400 times closer to the Earth. </span><br />
<span style="font-size: large;">This means the Sun and the <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>Moon</b></a> appear to be the same size in the sky. Today people are advised never to look up at the Sun during an eclipse or they may damage their eyes permanently. This group is waiting on a beach in Hawaii to observe a total solar eclipse. They are wearing special glasses, but these really don’t make it any safer.

Auroras

Auroras are bright displays of shimmering light that appear at night over the North and South Poles.</span><br />
<span style="font-size: large;"> The Aurora Borealis is the Northern Lights, the aurora that appears above the North Pole.

The Aurora Australis is the Southern Lights, the aurora that appears above the South Pole.

Auroras are caused by streams of charged particles from the Sun known as the solar wind  crashing into the gases of the Earth’s atmosphere. </span><br />
<span style="font-size: large;"> Oxygen gas glows yellow-green when it is hit low in the atmosphere, and orange higher up.

Nitrogen gas glows bright red when hit normally, and bright blue when ionized.

Auroras form a halo of light over the poles all the time, but they are usually too faint to see. </span><br />
<span style="font-size: large;">They flare up brightly when extra bursts of energy reach the Earth’s atmosphere from the Sun.

Auroras appear at the poles and nowhere else in the world because there are deep cracks here in the Earth’s magnetic field .

Auroras are more spectacular when the solar wind is blowing strongly.

New York and Edinburgh get an average of ten aurora displays every year. </span><br />
<span style="font-size: large;"> The Northern Lights above the <b><a href="http://educational-wealth.blogspot.com/2014/01/worlds-regions.html" target="_blank">Arctic</a> </b>Circle are among nature’s most beautiful sights. Shimmering, dancing curtains of colour - bright green rays flashing with red, and streamers of white - blaze into the darkness of the polar night</span></div>

Sun and it’s rays

The Sun The sun Medium-sized star The Sun is a medium-sized star measuring 1,392,000 km across.The Sun weighs 20...

Neptune and uranus

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<span style="font-size: large;">Neptune </span></h3>
<span style="font-size: large;"> Neptune is the eighth planet out from the Sun, varying in distance from 4456 to 4537 million km.

Neptune was discovered in 1846 because two mathematicians, John Couch Adams in England and Urbain le Verrier in France, worked out that it must be there because of the effect of its gravity on the movement of Uranus.

Neptune is so far from the Sun that its orbit lasts 164.79 <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a> years. Indeed, it has not yet completed one orbit since it was discovered in 1846. </span><br />
<span style="font-size: large;">Like Uranus, Neptune has a surface of icy cold liquid methane (-210°C), and an atmosphere of hydrogen and helium.

This photo of Neptune was taken by the Voyager 2 spacecraft in 1989. The Great Dark Spot, and the little white tail of clouds, named Scooter by astronomers, are both clearly visible.

Unlike Uranus, which is almost perfectly blue, Neptune has white clouds, created by heat inside the planet. </span><br />
<span style="font-size: large;"> Neptune has the strongest winds in the

Solar System, blowing at up to 700 m per second.

Neptune has eight moons, each named after characters from Ancient Greek myths - Naiad, Thalassa, Despoina, Galatea,

Larissa, Proteus, Triton and Nereid.
Neptune’s moon

Neptune’s moon Triton looks like a green melon, while its icecaps of frozen nitrogen look like pink ice cream.</span><br />
<span style="font-size: large;"> It also has volcanoes that erupt fountains of <a href="http://educational-wealth.blogspot.com/2014/03/worlds-glaciers-and-ice-ages.html" target="_blank"><b>ice</b></a>.

Triton is the only moon to orbit backwards.

Triton, the biggest of Neptune’s eight moons, is gradually spiralling towards Neptune and in 10 million to 100 million years time will break up and form rings round the planet. Triton’s geysers shoot out frozen nitrogen gas. </span><br />
<span style="font-size: large;">The Solar System’s largest moon is bigger than Planets </span><br />
<span style="font-size: large;">Neptune is the eighth planet out from the Sun, varying in distance from 4456 to 4537 million km. Neptune was discovered in 1846 because two mathematicians, John Couch Adams in England and Urbain le Verrier in France, worked out that it must be there because of the effect of its gravity on the movement of Uranus. Neptune is so far from the Sun that its orbit lasts 164.79 Earth years. Indeed, it has not yet completed one orbit since it was discovered in 1846.</span><br />
<span style="font-size: large;"> Like Uranus, Neptune has a surface of icy cold liquid methane (-210°C), and an atmosphere of hydrogen and helium. This photo of Neptune was taken by the Voyager 2 spacecraft in 1989. The Great Dark Spot, and the little white tail of clouds, named Scooter by astronomers, are both clearly visible. Unlike Uranus, which is almost perfectly blue, Neptune has white clouds, created by heat inside the planet. </span><br />
<span style="font-size: large;">Neptune has the strongest winds in the Solar System, blowing at up to 700 m per second. Neptune has eight moons, each named after characters from Ancient Greek myths - Naiad, Thalassa, Despoina, Galatea, Larissa, Proteus, Triton and Nereid. Neptune’s moon Neptune’s moon Triton looks like a green melon, while its icecaps of frozen nitrogen look like pink ice cream. </span><br />
<span style="font-size: large;">It also has volcanoes that erupt fountains of ice. Triton is the only moon to orbit backwards. Triton, the biggest of Neptune’s eight moons, is gradually spiralling towards Neptune and in 10 million to 100 million years time will break up and form rings round the planet. </span><br />
<span style="font-size: large;">Triton’s geysers shoot out frozen nitrogen gas. orbiting Jupiter. The Solar System’s largest moon, it is bigger than <a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank"><b>Planets</b></a> Neptune is the fourth largest planet. At 49,528 km across, it is slightly smaller than Uranus - hut it is actually a little heavier. </span><br />
<span style="font-size: large;">Like Uranus, its oceans of incredibly cold liquid methane make it a beautiful shiny blue, although Neptune's surface is a deeper blue than that of Uranus. Again like Uranus, Neptune has a thin layer of rings. But Neptune’s are level, and not at right angles to the Sun. Neptune has a Great Dark Spot, like Jupiter’s Great Red Spot, where storms whip up swirling clouds.</span><br />
<span style="font-size: large;"> Neptune’s moon Triton is the coldest place in the Solar System, with surface temperatures of -236°C There are little white tail of clouds and great dark spots on Neptune. These clouds are named scooter by scientists. These can clearly be seen in this photo taken by Voyager 2 space craft in 1989. Uranus Uranus is the seventh planet out from the Sun. Its orbit keeps it 1784 million km away on average and takes 84 years to complete.</span><br />
<span style="font-size: large;"> Uranus tilts so far on its side that it seems to roll around the Sun like a gigantic bowling ball. The angle of its tilt is 98°, in fact, so its equator runs top to bottom. This tilt may be the result of a collision with a meteor or another planet a long time ago. In summer on Uranus, the Sun does not set for 20 years. In winter, darkness lasts for over 20 years. </span><br />
<span style="font-size: large;">In autumn, the Sun rises and sets every nine hours. Uranus has 17 moons, all named after characters in William Shakespeare’s plays. There are five large moons - Ariel,Umbriel, Titania, Oberon and Miranda. The ten smaller ones were discovered by the Voyager 2 space probe in 1986. </span><br />
<span style="font-size: large;">Uranus’ moon Miranda is the weirdest moon of all. It seems to have been blasted apart, then put itself back together again! Because Uranus is so far from the Sun, it is very, very cold, with surface temperatures dropping to -210°C. Sunlight takes just eight minutes to reach Earth, but 2.5 hours to reach Uranus. Uranus’ icy atmosphere is made of hydrogen and helium. Winds whistle around the planet at over 2000 km/h - ten times as fast as hurricaneson Earth.</span><br />
<span style="font-size: large;"> Uranus has its own, very faint set of rings Uranus has an atmosphere of hydrogen and helium gas Uranus’ surface is an ice-cold ocean of liquid methane (natural gas), thousands of kilometres deep, which gives the planet its beautiful colour. If you fell into this ocean even for a fraction of a second, you would freeze so hard that you would shatter like glass. </span><br />
<span style="font-size: large;">Uranus was named after Urania, the ancient Greek goddess of astronomy. A Uranus is the third largest planet in the Solar System - 51,118 km across and with a mass 14.54 times that of the Earth’s. The planet spins round once every 17.24 hours, hut because it is lying almost on its side, this has almost no effect on the length of its day. Instead, this depends on where the planet is in its orbit of the Sun.</span><br />
<span style="font-size: large;"> Like Saturn, Uranus has rings, but they are much thinner and were only detected in 1977. They are The planet’s surface made of the darkest material in the Solar System. of liquid methane gives it a stunning blue colour Uranus is only faintly visible from Earth. It looks no bigger than a star through a telescope, and was not identified until 1781 (see Herschel). On Uranus in spring, the Sun sets every nine hours span style font-size: large;Neptune is the fourth largest planet.</span><br />
<span style="font-size: large;"> At 49,528 km across, it is slightly smaller than Uranus - hut it is actually a little heavier. Like Uranus, its oceans of incredibly cold liquid methane make it a beautiful shiny blue, although Neptune's surface is a deeper blue than that of Uranus.

Again like Uranus, Neptune has a thin layer of rings. But Neptune’s are level, and not at right angles to the Sun. </span><br />
<span style="font-size: large;">Neptune has a Great Dark Spot, like Jupiter’s Great Red Spot, where storms whip up swirling clouds.

Neptune’s moon Triton is the coldest place in the Solar System, with surface temperatures of -236°C

There are little white tail of clouds and great dark spots  on Neptune. </span><br />
<span style="font-size: large;">These clouds are named scooter by scientists. These can clearly be seen in this photo taken by Voyager 2 space craft  in 1989.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Uranus </span></h3>
<span style="font-size: large;">Uranus is the seventh planet out from the Sun. Its orbit keeps it 1784 million km away on average and takes 84 years to complete.

Uranus tilts so far on its side that it seems to roll around the Sun like a gigantic bowling ball.</span><br />
<span style="font-size: large;"> The angle of its tilt is 98°, in fact, so its equator runs top to bottom. This tilt may be the result of a collision with a meteor or another planet a long time ago.

In summer on Uranus, the Sun does not set for 20 years. In winter, darkness lasts for over 20 years. In autumn, the Sun rises and sets every nine hours.</span><br />
<span style="font-size: large;"> Uranus has 17 moons, all named after characters in William Shakespeare’s plays. There are five large moons - Ariel,Umbriel, Titania, Oberon and Miranda. The ten smaller ones were discovered by the Voyager 2 space probe in 1986.

Uranus’ moon Miranda is the weirdest <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>moon</b></a> of all.</span><br />
<span style="font-size: large;"> It seems to have been blasted apart, then put itself back together again!

Because Uranus is so far from the Sun, it is very, very cold, with surface <a href="http://educational-wealth.blogspot.com/2014/02/temprature-of-earth.html" target="_blank"><b>temperature</b></a>s dropping to -210°C. Sunlight takes just eight minutes to reach Earth, but 2.5 hours to reach Uranus.

Uranus’ icy atmosphere is made of hydrogen and helium.

Winds whistle around the planet at over 2000 km/h - ten times as fast as hurricaneson Earth. </span><br />
<span style="font-size: large;">Uranus has its own, very faint set of rings

Uranus has an atmosphere of hydrogen and helium gas

Uranus’ surface is an ice-cold ocean of liquid methane (natural gas), thousands of kilometres deep, which gives the planet its beautiful colour. If you fell into this ocean even for a fraction of a second, you would freeze so hard that you would shatter like glass.</span><br />
<span style="font-size: large;"> Uranus was named after Urania, the ancient Greek goddess of astronomy.

A Uranus is the third largest planet in the Solar System - 51,118 km across and with a mass 14.54 times that of the Earth’s. The planet spins round once every 17.24 hours, hut because it is lying almost on its side, this has almost no effect on the length of its day. </span><br />
<span style="font-size: large;">Instead, this depends on where the planet is in its orbit of the Sun. Like <a href="http://educational-wealth.blogspot.com/2014/02/very-beautiful-saturn-rings.html" target="_blank"><b>Saturn</b></a>, Uranus has rings, but they are much thinner and were only detected in 1977. They are The planet’s surface made of the darkest material in the Solar System.

of liquid methane gives it a stunning blue colour

Uranus is only faintly visible from Earth. It looks no bigger than a star through a telescope, and was not identified until 1781 (see Herschel).

On Uranus in spring, the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> sets every nine hours

</span></div>

Neptune and uranus

Neptune Neptune is the eighth planet out from the Sun, varying in distance from 4456 to 4537 million km. Neptune was discovered in 184...

planets, orbits

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<h3 style="text-align: left;">
<span style="font-size: large;">Planets </span></h3>
<span style="font-size: large;">Planets are globe-shaped space objects that orbit a star.

Planets begin life at the same time as their star, from the left over clouds of gas and dust.

Planets are never more than 20 percent of the size of their star. Some planets, called terrestrial planets, have a surface of solid rock. </span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg888v3jqLlplvrKB213G4ePhbI4gUdm5mE8VuHfUBSjpdA54HKAcmBr8XdZ-Q6DNdxOZV7zJ0ClzkA3l2oGH1hIX7Gz87L-IskUCkfmaOapQLcYlFk1AwBnX6Tc9Jv4BjIk2qLXJiUN8M/s1600/pplanet.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="396" loading="lazy" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg888v3jqLlplvrKB213G4ePhbI4gUdm5mE8VuHfUBSjpdA54HKAcmBr8XdZ-Q6DNdxOZV7zJ0ClzkA3l2oGH1hIX7Gz87L-IskUCkfmaOapQLcYlFk1AwBnX6Tc9Jv4BjIk2qLXJiUN8M/s1600-rw/pplanet.bmp" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">planets in orbits</td></tr>
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<br />
<span style="font-size: large;">Others, called gas planets, have a surface of liquid or airy gas.

The solar system has nine planets including Pluto. But Pluto may be an escaped moon or an asteroid, not a planet.

Giant planets have now been detected orbiting stars other than the Sun. These are called extra-solar planets.

Extra-solar planets are too far away to see, but can be detected because they make their star wobble.

One extra-solar planet has now been photographed. Among the nine stars so far known to have planets are 47 Ursae Majoris, 51 Pegasi, and 70 Virginis.</span><br />
<span style="font-size: large;"> Four of the new planets - called 51 Peg planets, after the planet that circles 51 Pegasi - seem to orbit their stars in less than 15 days. The planet orbiting Tau Bootis gets around in just 3.3 days.

A Most of the nine planets in our Solar System have been known since ancient times, but in the last few years planets have been found orbiting other, far away stars.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> The planets of our Solar System: </span></h3>
<span style="font-size: large;">from the front,<a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b> Neptune</b></a>, <a href="http://educational-wealth.blogspot.com/2014/02/two-most-important-planetsneptune-and.html" target="_blank"><b>Uranus</b></a>, <a href="http://educational-wealth.blogspot.com/2014/02/very-beautiful-saturn-rings.html" target="_blank"><b>Saturn</b></a>, Jupiter, <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Mars</b></a>, Earth and its <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>moon</b></a>, <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Venus</b></a> and Mercury. Pluto (not shown) is the furthest out from the Sun.

These all planets move in orbits around the sun.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Orbits</span></h3>
<span style="font-size: large;"> Orbit means ‘travel round’, and a moon, planet or other space object may be held within a larger space object’s gravitational field and orbit it.</span><br />
<span style="font-size: large;"> Space stations are artificial satellites that orbit the Earth. The Moon is the Earth’s natural satellite.

Orbits may be circular, elliptical (oval) or parabolic (conical). The orbits of the planets are elliptical.

An orbiting space object is called a satellite. </span><br />
<span style="font-size: large;"> The biggest-known orbits are

those of the stars in the Milky Way, which can take 200 million or more years.

Momentum is what keeps a satellite moving in space. How much momentum a satellite has depends on its mass and its speed. </span><br />
<span style="font-size: large;">A satellite orbits at the height where its momentum exactly balances the pull of the larger object’s gravity.

If the gravitational pull is greater than a satellite’s momentum, it falls in towards the larger space object.

If a satellite’s momentum is greater than the pull of the larger object’s gravity, it flies off into space. </span><br />
<span style="font-size: large;">The lower a satellite orbits, the faster it must travel to stop it falling in towards the larger space object.

Geostationary orbit for one of Earth’s artificial satellites is 35,786 km over the Equator. At this height, it must travel around 11,000 km/h to complete its orbit in 24 hours. </span><br />
<span style="font-size: large;">Since <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a> also takes 24 hours to rotate, the satellite spins with it and so stays in the same place over the Equator.

Earth is about 150 million km from the Sun. However, this distance varies as our planet's orbit is slightly oval. The time it takes for Earth to orbit the Sun once is 365 days. In comparison, Pluto takes 248 years to orbit the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a>. </span></div>

planets, orbits

Planets Planets are globe-shaped space objects that orbit a star. Planets begin life at the same time as their star, from the left over...

saturn (planet)

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<h3 style="text-align: left;">
<span style="font-size: large;">Saturn </span></h3>
<span style="font-size: large;">Saturn is the second biggest planet in the Solar System - 815 times as big in volume as the Earth, and measuring 120,000 km around its equator.

Saturn takes 29 and a half years to travel round the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a>, so Saturn’s year is 29.46 Earth years. The planet’s complete orbit is a journey of more than 4.5 billion km.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Winds on saturn </span></h3>
<span style="font-size: large;"> Winds ten times stronger than a hurricane on Earth swirl around Saturn’s equator, reaching up to 1,100 km/h - and they never let up, even for a moment. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> </span><span style="font-size: large;">Ancient Roman god of seed-time</span></h3>
<span style="font-size: large;"> Saturn is named after Saturnus, the Ancient Roman god of seed-time and harvest. </span><br />
<span style="font-size: large;">He was celebrated in the Roman’s wild, Christmas-time festival of Saturnalia.

Saturn is not solid, but is made almost entirely of gas - mostly liquid hydrogen and helium. Only in the planet’s very small core is there any solid rock.

Because Saturn is so massive, the pressure at its heart is enough to turn hydrogen solid. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">speed of saturn </span></h3>
<span style="font-size: large;">That is why there is a layer of metallic hydrogen around the planet’s inner core of <a href="http://educational-wealth.blogspot.com/2014/02/rocks-of-earth.html" target="_blank"><b>rock</b></a>.

Saturn is one of the fastest spinning of all the planets.

Despite its size, it rotates in just 11.5 hours - which means it turns round at over 10,000 km/h. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Density of saturn </span></h3>
<span style="font-size: large;">Saturn is so low in density that if you could find a bath big enough, you would be able to float the planet in the water.Saturn’s rings are made of many millions of tiny, ice-coated rock fragments

to be almost completely smooth, though Voyager 1 and 2 did photograph a few small, swirling storms when they flew past.

Saturn has a very powerful magnetic field  and sends out strong radio signals.

Saturn is almost as big as Jupiter.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Saturn's beautiful rings </span></h3>
<span style="font-size: large;"> Made largely of liquid hydrogen and helium, Saturn is stunningly beautiful, with its smooth, butterscotch surface (clouds of ammonia) and its shimmering halo of rings. But it is a very secretive planet. <a href="http://educational-wealth.blogspot.com/2014/02/space-telescopes-and-crafts.html" target="_blank"><b>Telescope</b></a>s have never pierced its upper atmosphere, and data from the Voyager probes focused on its rings and moons. But the Cassini probe, launched in 1997, may change this when it eventually descends into Saturn’s atmosphere

Saturn’s rings are sets of thin rings of ice, dust and tiny rocks, which orbit the planet around its equator.

The rings shimmer as their ice is caught by sunlight.

Saturn’s rings are one of the wonders of the Solar System, and many people think they make it the most beautifid planet.

The rings may be fragments of a moon that was torn apart by Saturn’s gravity before it formed properly.

Galileo was first to see Saturn’s rings, in 1610. But it was Dutch scientist Christian Huygens (1629-95) who first realized they were rings, in 1659.

There are two main sets of rings - the A and the B rings. </span><br />
<span style="font-size: large;">The A and B rings are separated by a gap called the Cassini division, after Italian astronomer Jean Cassini (1625-1712), who spotted it in 1675.

A third large ring called the C or crepe ring was spotted closer to the planet in 1850.

In the 1980s, space probes revealed many other rings and 10,000 or more ringlets, some just 10 m wide. </span><br />
<span style="font-size: large;"> The rings are (in order out from the planet) D, C, B, Cassini division, A, F, G and E.

Planets  Seen up close it becomes clear that Saturn’s rings are made up of dust, rocks and ice, shimmering in sunlight. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Saturn’s moon </span></h3>
<span style="font-size: large;">Enceladus is marked by deep valleys, suggesting geological activity. This is quite rare in moons and smaller planets.

The second largest is Saturn’s moon Titan. This moon is rather like a small frozen Earth, with a rocky core beneath a cold, nitrogen atmosphere.

Saturn’s moon Iapetus is white on one side and black on the other.

Saturn’s <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>moon</b></a> Enceladus is only 500 km across, and glistens because it is covered in beads of ice.

</span></div>

saturn (planet)

Saturn Saturn is the second biggest planet in the Solar System - 815 times as big in volume as the Earth, and measuring 120,000 km aroun...

Mercury and pluto (planets)

Abdullah 0 Article, Astronomy Wednesday, February 05, 2014

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<span style="font-size: large;">Pluto</span></h3>
<span style="font-size: large;"> Pluto was the last of all the planets to be discovered, and it was only found because it has a slight effect on the orbits of Neptune and Uranus.

Pluto is the furthest out of all the planets, varying from 4730 to 7375 million km from the Sun.

The Sun is so far from Pluto that if you could stand on the planet’s surface, the Sun would look no bigger than a star in Earth’s sky and shine no more brightly than the Moon does. </span><br />
<span style="font-size: large;">A Pluto is tiny in comparison to the Earth, which is why it was so hard to find. Earth is five times bigger and 500 times as heavy.

This illustration shows the relative sizes of the Earth and Pluto.

Pluto’s orbit is so far from the Sun that it takes 248.54 years just to travel right around once. This means that a year on Pluto lasts almost three Earth centuries.</span><br />
<span style="font-size: large;"> A day, however, lasts just under a week.

Pluto has a strange elliptical (oval) orbit which actually brings it closer to the Sun than Neptune for a year or two every few centuries.

Unlike all the other planets which orbit on exactly the same plane (level) as the Earth,Pluto’s orbit cuts across diagonally.

While studying a photo of Pluto in 1978,

American astronomer James Christy noticed a bump. </span><br />
<div style="text-align: left;">
<span style="font-size: large;">This turned out to be a large moon, which was later named Charon.

Charon is about half the size of Pluto and they orbit one another, locked together like a weightlifter’s dumbbells.

Charon always stays in the same place in Pluto’s sky, looking three times as big as our Moon Unlike the other outer planets, Pluto is made from rock. But the <a href="http://educational-wealth.blogspot.com/2014/02/rocks-of-earth.html" target="_blank"><b>rock</b></a> is covered in water, <a href="http://educational-wealth.blogspot.com/2014/03/worlds-glaciers-and-ice-ages.html" target="_blank">ice</a> and a thin layer of frozen methan

Daytime temperatures on Pluto’s surface are -220°C or less, so the surface is thought to be coated in frozen methane. </span></div>
<span style="font-size: large;"> This picture of Pluto is entirely imaginary, since it is so small and so far away that even photographs from the Hubble space <a href="http://educational-wealth.blogspot.com/2014/02/space-telescopes-and-crafts.html" target="_blank"><b>telescope</b></a> show no more detail on Pluto’s surface than you could see on the surface of a billiard ball. However, a twinkling of starlight around the edge of the planet shows that it must have some kind of atmosphere.

Pluto was discovered on 18 February 1930 by young American astronomer Clyde Tombaugh.</span><br />
<span style="font-size: large;"> The largest moon in the Solar System is Jupiter’s moon Ganymede.

The smallest moons are rocky lumps just a few kilometres across, rather like asteroids. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Mercury </span></h3>
<span style="font-size: large;">Mercury is the nearest planet to the Sun - during its orbit it is between 45.9 and 69.7 million km away.

Mercury is the fastest orbiting of all the <a href="http://educational-wealth.blogspot.com/2014/02/what-are-planets.html" target="_blank"><b>planets</b></a>, getting around the Sun in just 88 days.once, so a Mercury day lasts nearly 59 times.

Mercury takes 58.6 days to rotate as long as ours. <a href="http://educational-wealth.blogspot.com/2014/02/temprature-of-earth.html" target="_blank"><b>Temperature</b></a>s on Mercury veer from -180°C at night to over 430°C during the day (enough to melt lead). </span><br />
<span style="font-size: large;">The crust and mantle are made largely of rock, but the core (75 percent of its diameter) is solid iron.

Mercury’s dusty surface is pocketed by craters made by space debris crashing into it .Mercury is a tiny planet with a thin atmosphere and a solid core.

With barely 20 percent of <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank"><b>Earth</b></a>’s mass, Mercury is so small that its

gravity can only hold on to a very thin atmosphere of sodium vapour. </span><br />
<span style="font-size: large;">Mercury is so small that its core has cooled and become solid (unlike Earths). </span><br />
<span style="font-size: large;">As this happened, Mercury shrank and its surface wrinkled like the skin of an old apple.

Craters on Mercury discovered by the USAs Mariner space probe have names like Bach, Beethoven, Wagner, Shakespeare and Tolstoy. </span><br />
<span style="font-size: large;">Mercury gets very close to the Sun and speeds up so much that the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> seems to go backwards in the sky.</span><br />
<span style="font-size: large;"> Mercury is a planet of yellow dust, as deeply dented with craters as the <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>Moon</b></a>. It does have small polar icecaps, but the ice is pure acid.

The largest feature on Mercury is a huge impact crater called the Caloris Basin, which is about 1300 km across and 2 km deep.

Mercury’s surface is covered with impact craters. Most were formed by the impact of debris left over from the birth of the Solar System, about 4 billion years ago.

</span></div>

Mercury and pluto (planets)

Pluto Pluto was the last of all the planets to be discovered, and it was only found because it has a slight effect on the orbits of Nept...

Travel to space

Abdullah 0 Article, Astronomy Monday, February 03, 2014

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<h3 style="text-align: left;">
<span style="font-size: large;">Extra Vehicular Activity (EVA )</span></h3>
<span style="font-size: large;">The technical name for going outside a spacecraft is Extra-Vehicular Activity (EVA).

In 1965 Soviet cosmonaut Alexei Leonov was the first person ever to walk in space. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Space suits </span></h3>
<span style="font-size: large;">Space suits protect astronauts when they go outside their spacecraft. The suits are also called EMUs (Extra-vehicular Mobility Units).

The outer layers of a space suit protect against harmful radiation from the Sun and bullet-fast particles of space dust called micrometeoroids. </span><br />
<span style="font-size: large;"> The clear, plastic helmet also protects against radiation and micrometeoroids.

Oxygen is circulated around the helmet to stop the visor misting.

The middle layers of a space suit are blown up like a balloon to gently hold the astronaut’s body. Small astronauts actually have room to ‘float’ inside their space suits. </span><br />
<span style="font-size: large;">The soft inner lining of a space suit has tubes of water in it to cool the astronaut’s body or warm it up.

The backpack supplies pure oxygen for the astronaut to breathe, and gets rid of the carbon dioxide he or she gives out. </span><br />
<span style="font-size: large;">The oxygen comes from tanks which hold enough for up to seven hours.

The gloves have silicone-rubber fingertips which allow the astronaut some sense of touch.

Various different gadgets in the suit deal with liquids - including a tube for drinks and another for collecting urine.</span><br />
<span style="font-size: large;"><b>Cost of space suit</b> </span><br />
<span style="font-size: large;"> The full cost of a spacesuit is about $11 million although 70 percent of this is for the backpack and control module. </span><br />
<h3 style="text-align: left;">
<b><span style="font-size: large;">Space stations </span></b></h3>
<span style="font-size: large;">The first space station was the Soviet Salyut 1, launched in April 1971. Its low orbit meant it stayed up only five months.

The first US space station was Skylab. </span><br />
<span style="font-size: large;">Three crews spent 171 days in it in 1973-74.

The longest serving station was the Soviet Mir - launched in 1986, it made more than 76,000 orbits of the Earth. The last crew left in late 1999.

Mir was built in stages. It weighed 125 tonne's and had six docking ports and two living rooms, plus a bathroom and two small individual cabins.

There is neither an up nor a down in a space station, but Mir had carpets on the ‘floor’, pictures on the ‘wall’ and lights on the ‘ceiling’. </span><br />
<span style="font-size: large;">The US space station Skylab was launched in 1973 and lasted until 1979.

Cosmonaut Valery Polyakov spent a record 437 days in a row in space on Mir.

The giant International Space Station (ISS) is being built in stages and should be complete in 2010.

The first crew went aboard the ISS in November 2000.</span><br />
<span style="font-size: large;"> The longest spells of EVA were by astronauts working from the Space Shuttle for eight hours and 29 minutes.

The first space walkers were tied to their spacecraft by life-support cables.

Now a days, most space walkers use a Manned Manoeuvring Unit (MMU)- a huge, rocket-powered backpack that lets them move about freely.

In 1984, US astronaut Bruce McCandless was the first person to use an MMU in space.</span><br />
<span style="font-size: large;"> Damages to the Mir space station and other satellites have been repaired by space-walking astronauts.

Russian and US astronauts will perform more than 1700 hours of space walks when building the International Space Station.</span><br />
<span style="font-size: large;">  The International Space Station (ISS) will be over 100 m long and will weigh 450 tonnes. Space walks will be essential to ensure the station is completed by 2004.

The SOHO space observatory is stationed between the Earth and the Sun, monitoring the Sun to find out about changes in solar activity. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Space exploration </span></h3>
<span style="font-size: large;">Space is explored in two ways - by studying it from <a href="http://educational-wealth.blogspot.com/2014/02/our-lovely-planetearth-creation-origin.html" target="_blank">Earth</a> using powerful <a href="http://educational-wealth.blogspot.com/2014/02/space-telescopes-and-crafts.html" target="_blank"><b>telescope</b></a>s, and by launching spacecraft to get a closer view. Most space exploration is by unmanned space probes. The first pictures of the far side of the Moon were sent back by the Luna 3 space probe in October 1959. </span><br />
<span style="font-size: large;">Manned missions have only reached as far as the Moon, but there may be a manned mission to <a href="http://educational-wealth.blogspot.com/2014/02/mars-planet.html" target="_blank"><b>Mars</b></a> in 2020. Apollo astronauts took three days to reach the <a href="http://educational-wealth.blogspot.com/2014/02/moon-of-earth.html" target="_blank"><b>Moon</b></a>. </span><br />
<span style="font-size: large;">No space probe has ever come back from another planet.

The Atlas space rocket on the launch pad, ready to propel the highly advanced SOHO observatory into space.

This satellite observes the <a href="http://educational-wealth.blogspot.com/2014/02/sun-and-its-rays.html" target="_blank"><b>Sun</b></a> and also environmental changes and weather conditions on Earth

Travel to the stars would take hundreds of years, but one idea is that humans might go there inside gigantic spaceships made from hollowed-out asteroids.</span><br />
<span style="font-size: large;"> Another idea is that spacecraft on long voyages of exploration may be driven along by pulses of laser light. The Pioneer 10 and 11 probes carry metal plaques with messages for aliens telling them about us NASA may fund research on spacecraft that jump to the stars through wormholes .</span></div>

Travel to space

Extra Vehicular Activity (EVA ) The technical name for going outside a spacecraft is Extra-Vehicular Activity (EVA). In 1965 Soviet cos...

Hoiw meiosis takes place

Abdullah 0 Article Sunday, February 02, 2014

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<span style="font-size: large;">Meiosis </span></h3>
<div style="text-align: left;">
<span style="font-size: large;"> The preparatory steps of meiosis are identical to the interphase of the <a href="http://educational-wealth.blogspot.com/2014/02/phases-of-mitosis-process-of-mitosis-is.html" target="_blank"><b>mitosis</b></a>. Interphase is divided into the same three phases i.e. G1, S phase, and G2. Interphase is followed by meiosis I and meiosis II.</span></div>
<h3 style="text-align: left;">
<span style="font-size: large;"> Meiosis 1 </span></h3>
<span style="font-size: large;"> In meiosis I, the homologous chromosomes in a Thomas Hunt Morgan observed diploid cell separate and so two haploid daughter the phenomenon of crossing cells are produced. It is the step in meiosis that over in the fruit fly Drosophila generates genetic diversity. </span><br />
<span style="font-size: large;">Meiosis I occurs in two melanogaster. main steps i.e. karyokinesis and cytokinesis. </span><br />
<span style="font-size: large;"> The karyokinesis of Meiosis I is subdivided into prophase I, metaphase I, anaphase I, and telophase I. </span><br />
<h3>
<b><span style="font-size: large;">Prophase I: </span></b></h3>
<span style="font-size: large;"> Prophase I is the longest phase in meiosis. During this stage, individual chromosomes begin to condense within the nucleus. Then the homologous chromosomes line up with each other and form pairs. The combined homologous chromosomes are said to be bivalent. They may also be referred to as a tetrad, a reference to the four sister chromatids. </span><br />
<span style="font-size: large;">The two non-sister chromatids of homologous chromosomes become "zipped" together, forming complexes known as chiasmata, in a process known as synapsis. In the next stage, the non-sister chromatids of homologous chromosomes randomly exchange their segments and the phenomenon is known as crossing over .The exchange of segments results in a recombination of genetic information. After crossing over the homologous chromosomes separate from one another. </span><br />
<span style="font-size: large;">However, they remain tightly bound at chiasmata, the regions where crossing over occurred.

Chromosomes condense further, the nucleoli disappear, and the nuclear envelope disintegrates. Centrioles, which were duplicated during interphase, migrate to the two poles of the cell. </span><br />
<span style="font-size: large;">They give rise to spindle f chromosomes. While the non-kinetochore spindle fibres from botfibres. The kinetochore spindle fibres attach to the kinetochores oh sides interact with each other. There are two kinetochores on each tetrad, one for each kinetochore spindle fibre.

chromosomes

chromosomes </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Metaphase I: </span></h3>
<span style="font-size: large;">As kinetochore spindle fibers from both centrioles attach to their respective kinetochores, the homologous chromosomes align along an equatorial plane forming the metaphase plate. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Anaphase I: </span></h3>
<span style="font-size: large;">Kinetochore spindle fibers shorten, breaking the chiasmata and pulling homologous chromosomes apart. Since each chromosome only has one kinetochore, one chromosome is pulled toward one pole, forming two diploid sets. Each chromosom

Sister chromatids of a chromosome. </span><br />
<span style="font-size: large;">Nomsister chromatids of a homologous chromosome pair contains a pair of sister chromatids.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Telophase I: </span></h3>
<span style="font-size: large;">The first meiotic division ends when the chromosomes arrive at the poles. Each pole now has half the number of chromosomes but each chromosome still consists of a pair of chromatids. The spindle network disappears, and a new nuclear envelope surrounds each haploid set. </span><br />
<span style="font-size: large;">The chromosomes uncoil back into chromatin. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Cytokinesis</span></h3>
<span style="font-size: large;"> The pinching of the cell membrane in animal cells or the formation of the cell wall in plant cells, occurs, completing the creation of two daughter cells

After meiosis I both haploid daughter cells enter a period of rest known as interkinesis or icterphase II. The interphase II is different from the interphase of mitosis and meiosis I.</span><br />
<span style="font-size: large;"> There is no S-phase and so no DNA replication occurs during this stage.

During crossing over, genetic material is exchanged between sister/non-sister chromatids of homologous/non-homologous chromosomes. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">MEIOSIS </span></h3>
<span style="font-size: large;"> It is the second part of the meiotic process. Much of this part is similar to mitosis. </span><br />
<span style="font-size: large;">It is subdivided into prophase II, metaphase II, anaphase II, and telophase II.
Prophase II

It takes much less time compared to prophase I. In this prophase the nucleoli and the nuclear envelope disappear and the chromatin condenses. Centrioles move to the polar regions and make spindle fibres. </span><br />
<span style="font-size: large;">In metaphase II, the chromosomes attach with the kinetochore spindle fibers and align at the equator of the cell. This is followed by anaphase II, where the centromeres are cleaved and sister chromatids are pulled apart. </span><br />
<span style="font-size: large;">The sister chromatids are now called sister chromosomes, and they are pulled toward opposing poles. The telophase II is marked with uncoiling and disappearance of the chromosomes. </span><br />
<span style="font-size: large;">Nuclear envelopes reform; cleavage or cell wall formation eventually produces a total of 4 daughter cells, each with a haploid set of chromosomes . </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">SIGNIFICANCE OF MEIOSIS</span></h3>
<span style="font-size: large;"> The significance of meiosis for reproduction and inheritance was described in 1890 by German biologist August Weismann, who noted that meiosis was necessary to transform one diploid cell into four haploid cells if the number of chromosomes had to be maintained.

Meiosis is essential for reproduction and therefore occurs in all eukaryotes, including single-celled organisms that reproduce sexually. </span><br />
<span style="font-size: large;">Meiosis does not occur in archaea or prokaryotes, which reproduce asexually by binary fission. Humans, for example, are diploid creatures. The diploid gamete-mother cells undergo meiosis to produce haploid gametes, which are spermatozoa in males and ova in females. These gametes then fertilize, producing a diploid zygote. The zygote undergoes repeated mitosis and develops into the new organism</span><br />
<span style="font-size: large;"> Significance of meiosis in maintaining chromosome number constant

Male parent

Female parent

Many fungi and many protozoa are haploid. Such organisms produce haploid gametes through mitosis. When two gametes fuse they form diploid zygote, which undergoes meiosis immediately, creating four haploid cells. These cells undergo mitosis to create the haploid organism.</span><br />
<span style="font-size: large;"> Plants' life cycle shows alternation of generations. The cells of the diploid sporophyte generation undergo meiosis to produce haploid spores, which grow into haploid gametophyte generations. The haploid gametophyte generation produces haploid gametes through mitosis.</span><br />
<span style="font-size: large;"> The gametes combine to produce the diploid zygote. The zygote undergoes repeated mitosis to become the diploid sporophyte.

Because the chromosomes of each parent undergo genetic recombination during meiosis, each gamete, and thus each zygote, will have a unique genetic makeup. In other words, meiosis and sexual reproduction produce genetic variation. Thus meiosis allows a species to bring variations to handle the changes in the environment. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">ERRORS IN MEIOSIS </span></h3>
<span style="font-size: large;">The normal separation of chromosomes or sister chromatids in meiosis is termed as disjunction. When the separation is not normal, it is called nondisjunction. This results in the production of gametes which have either more or less than the usual number of chromosomes i.e. there may be trisomy (2n + 1) or monosomy (2n -1). </span><br />
<span style="font-size: large;">It causes several medical conditions in humans such as; Down's Syndrome (trisomy of chromosome 21), Klinefelter's Syndrome (an extra X chromosome in males), and Turner's Syndrome (only one X chromosome present in females). Such individuals have 45 or 57 chromosomes.

</span></div>

Hoiw meiosis takes place

Meiosis The preparatory steps of meiosis are identical to the interphase of the mitosis . Interphase is divided into the same three ph...

Way of reproduction (Mitosis)

Abdullah 0 Article, biology Sunday, February 02, 2014

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<span style="font-size: large;">Phases of mitosis </span></h3>
<span style="font-size: large;">The process of mitosis is complex and highly regulated. The sequence of events is divided into major phases</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Karyokinesis </span></h3>
<span style="font-size: large;">This is the division of the nucleus known as karyokinesis. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Cytokinesis </span></h3>
<span style="font-size: large;">This is the division of the cytoplasm known as cytokinesis. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Mitotic spindle</span></h3>
<h3 style="text-align: left;">
<span style="font-size: large;"> </span></h3>
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<tr><td class="tr-caption" style="text-align: center;">Mitosis</td></tr>
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<span style="font-size: large;">Microtubules thus formed are called spindle fibers, and the complete set of the spindle fibers is known as mitotic spindle. During the formation of mitotic spindle, the centrosomes migrate to opposite side of the nucleus. </span><br />
<span style="font-size: large;">The nucleolus and the nuclear envelope have degraded, and spindle fibers have invaded the central space.

In highly vacuolated plant cells, the nucleus has to migrate into the center of the cell before prophase. The cells of plants lack centrioles. Instead, spindle fibers are formed by the aggregation of tubulin proteins on the surface of the nuclear envelope during prophase. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Metaphase: </span></h3>
<span style="font-size: large;">When the spindle grows to sufficient length, some of the spindle fibers, known as kinetochore fibers, begin searching for kinetochores to attach. When kinetochore fibers attach to kinetochores, the centromeres of the chromosomes arrange themselves along the equator of the cell forming a metaphase plate. A number of other fibers (nonkinetochore) interact with the correspondingfibers from the opposite centrosome.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Anaphase</span></h3>
<span style="font-size: large;"> When a kinetochore spindle fibre connects with the kinetochore of the chromosome, it starts to pull toward the originating centrosomes. The pulling force divides the chromosome's sister chromatids, allowing them to separate. </span><br />
<span style="font-size: large;">These sister chromatids are now sister chromosomes, and they are pulled apart by shortening of the kinetochore spindle fibres toward the respective centrosomes. Next, the other spindle fibres (without kinetochore) elongate, pushing the centrosomes and the sets of chromosomes apart to opposite ends of the cell. At the end of anaphase, the cell has succeeded in separating identical copies of the genetic material into two distinct groups.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Telophase: </span></h3>
<span style="font-size: large;"> Telophase is a reversal of prophase. A new nuclear envelope forms around each set of separated sister chromosomes. Both sets of chromosomes, now surrounded by new nuclear envelopes, unfold back into chromatin. Nuclear division is complete, but cell division has yet one more step to complete. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Cleavage</span></h3>
<span style="font-size: large;">Cytokinesis is the division of the cytoplasm. In animal cells, cytokinesis occurs by a process known as cleavage. A cleavage furrow develops where the metaphase plate used to be. At the site of the furrow, the cytoplasm has a ring of microfilaments (a part of the cytoskeleton). </span><br />
<span style="font-size: large;">The ring contracts deepening the furrow and eventually pinching the parent cell into two. </span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Cytokinesis in plant cells </span></h3>
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<tr><td class="tr-caption" style="text-align: center;">cytokinesis in plant cell</td></tr>
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<br />
<span style="font-size: large;">Cytokinesis in plant cells occurs differently. Vesicles derived from the Golgi apparatus move to the middle of the cell and fuse to form a membrane-bounded disc called the cell plate or phragmoplast.</span><br />
<span style="font-size: large;"> The plate grows outward and more vesicle fuse with it. Finally, the membranes of the cell plate fuse with the plasma membrane and its contents join the parental cell wall. The result is two daughter cells, each bounded by its own plasma membrane and cell wall .</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;">Break down of nuclear membrane </span></h3>
<span style="font-size: large;"> Nuclear membrane breaks during cell division so there is no distinct nucleus.</span><br />
<h3 style="text-align: left;">
<span style="font-size: large;"> Interphase </span></h3>
<span style="font-size: large;"> In interphase nuclear material is in the form of fine chromatin which condenses during prophase to get the shape of chromosome.There are several features unique to <a href="http://educational-wealth.blogspot.com/2014/02/hoiw-meiosis-takes-place.html" target="_blank"><b>meiosis</b></a>, most importantly the pairing and genetic recombination between homologous chromosomes.

</span></div>

Way of reproduction (Mitosis)

Phases of mitosis The process of mitosis is complex and highly regulated. The sequence of events is divided into major phases Karyoki...

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Hoiw meiosis takes place

Way of reproduction (Mitosis)

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