astrophysics

n. study of the physical and chemical composition of celestial bodies

Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.
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The scientific discipline which seeks to explain why celestial objects, and the universe in general, behave in the way that they do. It relies on the assumption that the laws of physics are the same everywhere in the universe and throughout all time. See also astronomy.

Noun
1. the branch of astronomy concerned with the physical and chemical properties of celestial bodies
(hypernym) astronomy, uranology
(hyponym) cosmology, cosmogony, cosmogeny