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 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. 


 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 planets 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. 
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. 
 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. clip_image002 Rotation in universe The sun is approximately 150 000 000 kilometres (93 000 000 miles) from earth. 
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.
 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. 
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. 
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. 
 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 Africa, or perhaps far north in the Arctic regions. 
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.
 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. 
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. 
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 ice cap could cause coastal flooding. Generally speaking most authorities believe that it is essential that we all work together to rectify this problem. 
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. 
Since then, the problem has gotten progressive worse. Exposure to an overabundance of ultraviolet rays can leac to all kinds of problems - from severe sunburn 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. 
 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.

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