What is the knowledge of astronomy, wait online?

Astronomy, is the observation and study of the universe between the celestial bodies of the discipline, it is the study of the distribution of celestial bodies, movement, location, state, structure, composition, nature and the origin and evolution of the natural sciences, is a basic discipline.

The object of astronomy involves a variety of objects in cosmic space, from the moon to the extragalactic star system to the entire universe, or small from asteroids, meteoroids to the distribution of the vast cosmic space in the dust, particles, small and large. Astronomers refer to all these objects collectively as "celestial bodies".

The universe of celestial bodies from near and far can be divided into several levels: (1) solar system objects: including the sun, planets (including the Earth), planets, satellites (including the moon), asteroids, comets, meteoroids and interplanetary medium. (2) Various types of stars and stellar groups in the Milky Way: including variable stars, binaries, cluster stars, star clusters, nebulae, and the interstellar medium. (3) Extragalactic galaxies, or galaxies for short, refer to massive stellar systems located outside of our Milky Way that are similar to our Milky Way, as well as larger groups of objects made up of galaxies, such as binary galaxies, multiple galaxies, clusters of galaxies, and superclusters of galaxies. There is also an intergalactic medium distributed between galaxies.

Astronomy also explores the origin, structure, evolution, and future end of the entire universe that we observe in a general way, which is the study of cosmology, a subdiscipline of astronomy. Astronomy can also be divided into three subdisciplines, astrometry, celestial mechanics and astrophysics, according to the content of the study.

Astronomy has always been the forerunner of philosophy, and it has always stood at the forefront of controversy. As a basic research discipline, astronomy is in many ways closely related to human society. Time, the alternation of day and night, the strict laws of the seasons must be determined by astronomical methods. As mankind has entered the space age, astronomy plays an irreplaceable role in the successful conduct of all kinds of space exploration. Astronomy also makes its own contribution to disaster prevention and mitigation for mankind and the Earth.