is the science that deals with the study of celestial bodies in the universe , including planets and their satellites , comets and meteoroids , stars and interstellar matter , systems of dark matter, stars , gas and dust called galaxies and clusters galaxies . Registration and investigation of its origin comes from the information that reaches them through electromagnetic radiation or any other means .
In 16th century Poland, astronomer Nicolaus Copernicus (1473-1543) proposed a model of the solar system that involved the Earth revolving around the sun. The model wasn't completely correct, as astronomers of the time struggled with the backwards path Mars sometimes took, but it eventually changed the way many scientists viewed the solar system.
Using detailed measurements of the path of planets kept by Danish astronomer Tycho Brahe, Johannes Kepler (1571-1630) determined that planets traveled around the sun not in circles but in ellipses. In so doing, he calculated three laws involving the motions of planets that astronomers still use in calculations today.
Galileo Galilei is credited with discovering the first four moons of Jupiter.
Born in Italy, Galileo Galilei (1564-1642) is often credited with the creation of the optical telescope, though in truth he improved on existing models. The astronomer (also mathematician, physicist and philosopher) turned the new observational tool toward the heavens, where he discovered the four primary moons of Jupiter (now known as the Galilean moons), as well as the rings of Saturn. Though a model of the Earth circling the sun was first proposed by Copernicus, it took some time before it became widely accepted. Galileo is most widely known for defending the idea several years after Kepler had already calculated the path of planets, and Galileo wound up under house arrest at the end of his lifetime because of it.
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