TELESCOPES IN SPACE

Earth’s atmosphere is a real problem for astronomers. First, there are the clouds, of course.Then, air all by itself absorbs some of the light from outer space. The higher up you go, the more the air and the clouds are below you and the better you can see the sky above. Add in the effects of pollution and glare from city lights, and you can understand why big, new observatories are built on high mountains, far from big cities or factories, where the air is thin and dry. Even better would be to
have telescopes in space. The Hubble Space Telescope (HST) was not the first, but it’s the most
famous. It has a 95-inch (240 cm) mirror, so it’s much bigger than a backyard telescope. Being above
the atmosphere is what makes the HST so special. But there are dozens of observatories on mountaintops that have biggertelescopes than HST. It was named after Edwin Hubble, the astronomer who first measured the expansion of the universe.