Introduction to astronomical research

Objects and contents of astronomical research

Astronomers call all these stars and celestial bodies celestial bodies. In this sense, the earth should also be a celestial body, but astronomy only studies the general nature of the earth and generally does not discuss its details. On the other hand, the motion properties of artificial aircraft such as satellites, spaceships and space stations also belong to the research scope of astronomy and can be called artificial celestial bodies.

Many people often can't tell the difference between astronomy and meteorology. It is common to call the observatory to ask about the weather. Perhaps astronomy and meteorology are confused by studying things in the sky. The Hong Kong Observatory frequently broadcasts typhoon warnings, which makes people mistakenly think that the Observatory is studying weather conditions. In fact, the sky for astronomical research and the sky for meteorological research are two completely different concepts. Astronomical sky refers to space, and meteorological sky refers to the earth's atmosphere. Astronomers study the nature of various celestial bodies outside the earth's atmosphere and various phenomena that occur on celestial bodies-astronomical phenomena, while meteorologists study various phenomena that occur in the earth's atmosphere-meteorology. Therefore, it is an astronomer's business to predict the occurrence of solar eclipse, lunar eclipse and meteor shower, while it is a meteorologist's duty to predict typhoon, high temperature and cold wave. With this in mind, it is not difficult to distinguish astronomy from meteorology.

We can divide the celestial bodies in the universe into several levels from near to far:

(1) Celestial bodies in the solar system: including the sun, planets (including the earth), satellites of planets (including the moon), asteroids, comets, meteoroids and interplanetary media.

(2) Various stars and clusters in the Milky Way: including variable stars, binary stars, multi-stars, clusters, nebulae and interstellar media. The sun is an ordinary star in the Milky Way.

(3) Extragalactic galaxies, referred to as galaxies for short, refer to huge star systems similar to ours located outside our Milky Way galaxy, as well as large celestial bodies composed of galaxies, such as binary galaxies, multi-galaxies, galaxy clusters, supercluster clusters, etc. In addition, there are intergalactic media distributed between galaxies.

Astronomy also explores the origin, structure, evolution and future outcome of the universe as a whole, which is the research content of cosmology, a branch of astronomy.