Hubble EdwinHubble (1889-1953) was an American who trained in law at Chicago and Oxford, and was also a great boxer before he turned to astronomy. Until the early 20th century, astronomers thought that our galaxy was all there was to the Universe.
In the 1920s, Hubble showed that fuzzy patches of light once thought to be nebulae were in fact other galaxies far beyond the Milky Way. In 1929 Hubble measured the red shift of 18 galaxies, and showed that they were all moving away from us.
One of Hubble's earliest achievements was to show that some ‘nebulae’ were really other galaxies. Red shift showed Hubble that the further away a galaxy is, the faster it is moving. The ratio of a galaxy’s distance to the speed it is moving away from us is known as Hubble’s Law.
Hubble’s Law showed that the Universe is getting bigger - and so must have started very small. This led to the idea of the Big Bang. The figure given by Hubble’s law is Hubble’s constant and is about 40 to 80 km/sec per megaparsec. In the 1930s Hubble showed that the Universe is isotropic (the same in all directions).Hubble space telescope is named after Edwin Hubble.
GalileoGalileo Galilei (1564-1642) was a great Italian mathematician and astronomer.Galileo was born in Pisa on 15 February 1564, in the same year as William Shakespeare.
The pendulum clockThe pendulum clock was invented by-Galileo after watching a swinging lamp in Pisa Cathedral in 1583.
Galileo’s experiments with balls rolling down slopes laid the basis for our understanding of how gravity affects acceleration (speeding up).Learning of the telescope’s invention, Galileo made his own to look at the Moon, Venus and Jupiter. Galileo described his observations of space in a book called The Starry Messenger, published in 1613. One of the most brilliant scientists of all time, Galileo ended his life imprisoned (in his villa near Florence.Through his telescope Galileo saw that Jupiter has four moons (see Jupiter’s Galilean moons).
He also saw that Venus has phases (as our Moon does). Jupiter’s moon and Venus’s phases were the first visible evidence of Copernicus’ theory that the Earth moves round the Sun. Galileo also believed this. Galileo was declared a heretic in 1616 by the Catholic Church, for his support of Copernican theory.
Later, threatened with torture, Galileo was forced to deny that the Earth orbits the Sun. Legend has it he muttered eppur si muove’ (‘yet it does move’) afterwards. Galileo studied the skies through his telescope, which he demonstrated to members of the Venetian senate. Only on 13 October 1992 was the sentence of the Catholic Church on Galileo retracted. mm.