.
When astronomers go looking for new stars, comets or galaxies they use a number of different tools. To understand how these tools operate you must first understand the speed of light.
The distance light would travel in one year is 9460 billion km. For example, if you want to walk to the nearest star to us, Proxima Centauri, you better get started soon because its 40,678 billion km away, that is 4.3 light years. So when you view objects in the sky such as Proxima Centauri, you view them as they appeared 4.3 years ago, because that is how long its light took to reach us. .
Hale Telescope at Palomar Mtn (California) can detect objects less than one 10 millionth as bright as those the human eye can see.
Kitt Peak, Arizona-has a reflector 4 m (13ft) across. Kitt Peak also has the world's largest solar telescope.
Radio Telescopes- detect a wide range of signal sources, from exploding stars to interstellar molecules. Radio waves pass through our atmosphere very easily.
Pluto Express-radioisotope, powered by non-weapons grade plutonium. To be launched in 2002, and will send back images of Pluto and its moon, Charon in 2014.
Arecibo, Puerto Rico has the world's largest radioscope in the world at 305m (1000 ft) across. It can pick up signals from 15 billions light years away.
VLBA (Very Long Baseline Array) is a series of listening dishes that are linked together throughout N. America. Consisting of 10 receivers, each dish in the series is 82 ft wide. All the info is gathered together at Sorocco, NM, and is sorted out to act as 'one giant ear to the sky'.
Max Planck Institute-Bonn West Germany has a huge steerable radio telescope.
Microwave antennas can detect residual radiation from the Big Bang (13-15 billion yrs ago).
There are several types of satellites: