Telescope was used in 1609 for the first time to study the stars. Galileo Galilei, an Italian astronomer used the telescope to make many important discoveries. That includes seeing for the first time the four largest moons of Jupiter and the different phases of Venus. The Milky Way, made up of combined light of many thousands of distant stars were seen. Observations were then convinced that Earth and other planets went round the Sun. Galileo made his own telescopes.
Knowledge of the universe grew as telescopes improved. New types of telescopes were invented.One of the examples is the reflector, which uses a mirror, and not a lens, to collect light. The first was made by Issac Newton in 1668.
Kitt Peak National Observatory, Arizona, USA
Today, large telescopes are kept in special buildings called observatories. They are found in the USA, example there is Kitt Peak National Observatory, near Arizona. Astronomers who visit Kitt Peak come from all over the whole. They live there for a long time, studying the stars. Similar to this is the Cerro Tololo Inter-American Observatory, situated high on a mountain in South America.
Europeans astonomers carry out observations from La Palma, one of the Canary Islands. The observatory is situated 2,400 m above sea-level on an extinct volcano. Here astronomers take advantage of the dark, clear skies that are essential when observing the night sky.
William Herschel (1738-1822) was an amateur astronomer. He discovered the planet Uranuson 13th March 1781, using a telescope he had built. For many years he held the record for the largest telescope in the world