Astronomy DSST Free Study Guide with Questions and Answers

Heliocentric Theory Places the sun at the center of the solar system, stating that ll other bodies in the solar system orbit it. This was in direct contradiction to Ptolemy's geocentric theory, which stated Earth was the center of the Universe. Geocentric Theory Earth is the center of the Universe Nicolaus Copernicus Widely credited as the father of the heliocentric theory. Although he was not the first to propose the concept, his was the first mathematical model which correctly predicted the movement of the planets. He later published a book which was instrumental in making the idea popular. Hans Lippershey Usually credited as the inventor of the telescope (though it wasn't called that for many years later). He was a German-Dutch lens maker who first applied for the patent of the "Dutch Perspective Glass". It is important to note that, at the time, these were not used for astronomy. That came a little later with Galileo. Galileo Galilei Was the first to use a telescope for astronomical studies. He later used that telescope to discover the four largest moons of Jupiter. Galileo was a firm believer in the heliocentric theory. Since most scientists of the time and, more importantly, the Church embraced the geocentric theory, this caused Galileo much trouble and was the reason he was later placed under house arrest until his death. Celestial Sphere Theory In the early days of astronomy, there were plenty of theories like the geocentric theory which were later disproven. Another of these theories was something called the celestial sphere theory. This theory said that what we see in the sky was actually numerous spheres. You can think of the spheres as clear globes around the Earth with planets, comets and stars inside each of these globes. Some of these were thought to be in our own atmosphere and others were farther away. Even Copernicus, who got it so right with the Heliocentric theory, still believed in these celestial spheres. For example his model of the universe had the starts at equal distance from the Earth in one of the most distant spheres. Tycho Brahe Disproved the celestial sphere theory that all celestial objects were unmoving objects in Earth's sky. He demonstrated this was untrue through observation of a supernova, which he proved was beyond the solar system and thus not a phenomenon within Earth's atmosphere.