Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally, "law of the stars") is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions. Astronomical observations are ...

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In ancient Greece and other early civilizations, astronomy consisted largely of astrometry, measuring positions of stars and planets in the sky. Later, with the work of astronomers Kepler and Newton, whose work led to the development of celestial mechanics, the mathematical prediction of the motions of celestial bodies interacting gravitationally became the focus of astronomy. This was applied to solar system objects in particular. Motions and positions of objects are now more easily determined, and modern astronomy is more concerned with observing and understanding the actua ...

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Astronomy, Astronomy - Divisions, Astronomy - By subject or problem addressed, Astronomy - Ways of obtaining information, Astronomy - History of astronomy, Astronomy - Timelines in astronomy, Astronomy - Astronomy tools

Read more here: » Astronomy: Encyclopedia II - Astronomy - Divisions

In early times, astronomy only comprised the observation and predictions of the motions of the naked-eye objects. Aristotle said that the Earth was the center of the Universe and everything rotated around it in orbits that were perfect circles. Aristotle had to be right because people thought that Earth had to be in the center with everything rotating around it because the wind would not scatter leaves, and birds would only fly in one direction. For a long time, people thought that A ...

See also:

Astronomy, Astronomy - Divisions, Astronomy - By subject or problem addressed, Astronomy - Ways of obtaining information, Astronomy - History of astronomy, Astronomy - Timelines in astronomy, Astronomy - Astronomy tools

Read more here: » Astronomy: Encyclopedia II - Astronomy - History of astronomy