page_title: Astronomy
section_title: Renaissance to modern era
hierarchical_section_title: Astronomy / History of astronomy / Renaissance to modern era
caption_attribution_description: Moon phases
context_page_description: Astronomy is the scientific study of celestial bodies such as stars, planets, comets, and galaxies
  The objects studied include stars, galaxies, planets, moons, asteroids, comets and nebulae. Phenomena outside the Earth's atmosphere are also studied. That includes supernovae explosions, gamma ray bursts, and cosmic microwave background radiation. Astronomy concerns the development, physics, chemistry, meteorology and movement of celestial bodies, as well as the structure and development of the Universe.
  Astronomy is one of the oldest sciences. Ancient people used the positions of the stars to navigate, and to find when was the best time to plant crops. Astronomy is very similar to astrophysics. A related subject, cosmology, is concerned with studying the Universe as a whole, and the way the universe changed over time. Astronomy is not the same as astrology, the belief that motion of the stars and the planets may affect human lives.
  Since the 20th century there have been two main types of astronomy, observational and theoretical astronomy. Observational astronomy uses telescopes and cameras to observe or look at stars, galaxies and other astronomical objects.
context_section_description: During the renaissance a priest named Nicolaus Copernicus thought, from looking at the way the planets moved, that the Earth was not the center of everything. Based on previous works, he said that the Earth was a planet and all the planets moved around the sun. This brought back the old idea of heliocentrism. A physicist called Galileo Galilei built his own telescopes, and used them to look more closely at the stars and planets for the first time. He agreed with Copernicus. The Catholic Church decided that Galileo was wrong. He had to spend the rest of his life under house arrest. Heliocentric ideas were soon improved by Johannes Kepler and Isaac Newton who invented the theory of gravity.
  After Galileo, people made better telescopes and used them to see farther objects such as the planets Uranus and Neptune. They also saw how stars were similar to our Sun, but in a range of colours and sizes. They also saw thousands of other faraway objects such as galaxies and nebulae.
caption: Drawings of the Moon by Galileo. His drawings were more detailed than anyone before him because he used a telescope to look at the Moon.
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