In 1609, Galileo was the first person credited to use a telescope to observe the skies. It is almost impossible to say exactly because of the rise of Astrology and the telescopes at the time.
Tycho Brahe, is commonly believed to be the first. This is false due to the fact that Brahe never used a telescope. He used other instruments and a multitude of equations and theories.
Galileo.
He was not the first astronomer; there were plenty before him going back to the Babylonians at least. Galileo, however, was the first to use a telescope.
Galileo Galilei first used a telescope to look at the stars in 1609.
Galileo was the first astronomer to use a telescope to observe celestial objects in detail. This helped him make groundbreaking discoveries such as the moons of Jupiter and the phases of Venus, which provided strong evidence for the heliocentric model of the solar system.
Galileo Gailei is the first person credited with using the telescope for astronomical observations. He did not invent the telescope. He is the first to have seen moons going around Jupiter, the rings of Saturn (though he incorrectly identified them), and that the Moon had cliffs and craters.
Galileo I am not so sure he was the first, but he is the most famous.
telescope
Galileo Galilei was the first astronomer to make extensive use of the telescope for astronomy. He made several important discoveries, such as the moons of Jupiter and the phases of Venus, using his telescope in the early 17th century.
Astronomer's are people (scientists) who study celestial bodies. So by profession an astronomer uses a telescope and not a microscope.
Galileo in 1609
Probably Galileo Galilei (Astronomer and Physicist, 1564 -1642)
A telescope is the instrument an astronomer uses to study matter in space.