Astronomy is one of the oldest natural sciences in the world. It is the study of all extraterrestrial objects, that is, those existing outside the Earth or its atmosphere, such as the solar system that consists of our star, the sun, and the objects that orbit it, the Moon, galaxies, planets and comets.

It is not simply that a clear understanding is acquired of the movements of the great bodies which we regard as the system of the world, but it is that we are introduced to a perception of laws governing the motion of all matter, from the finest particle of dust to the largest planet or sun, with a degree of uniformity and constancy, which otherwise we could hardly have conceived. Astronomy is pre-eminently the science of order.

Astronomy is religion (天文即宗教).

Astronomy is perhaps the science whose discoveries owe least to chance, in which human understanding appears in its whole magnitude, and through which man can best learn how small he is.

Astronomy also investigates and explains the origin and evolution of the phenomena associated with such objects, like supernova explosions, gamma rays, quasars, blazars, pulsars and cosmic microwave background radiation.

The mathematical thermology created by Fourier may tempt us to hope that, as he has estimated the temperature of the space in which we move, me may in time ascertain the mean temperature of the heavenly bodies: but I regard this order of facts as for ever excluded from our recognition. We can never learn their internal constitution, nor, in regard to some of them, how heat is absorbed by their atmosphere. We may therefore define Astronomy as the science by which we discover the laws of the geometrical and mechanical phenomena presented by the heavenly bodies.

For astronomy is not only pleasant, but also very useful to be known: it cannot be denied that this art unfolds the admirable wisdom of God.

From astronomy we find the east, west, south, and north, as well as the theory of the heavens, the equinox, solstice, and courses of the stars. If one has no knowledge of these matters, he will not be able to have any comprehension of the theory of sundials.

Astronomy is a discipline that requires technical skills and cutting-edge technology . And these can be used to tackle environmental challenges such as climate change or to plan the long-term response to the current famine in southern Madagascar.

Astronomy was used to measure time, mark seasons and navigate oceans based on predictions about the positions of the sun, the Moon and the planets, while stars have helped people to navigate the Earth by lighting up the night.

Of all the sciences cultivated by mankind, Astronomy is acknowledged to be, and undoubtedly is, the most sublime, the most interesting, and the most useful. For, by knowledge derived from this science, not only the bulk of the Earth is discovered . . . ; but our very faculties are enlarged with the grandeur of the ideas it conveys, our minds exalted above [their] low contracted prejudices.

It is remarkable how much of the utilised information men possess has been derived from the observations of astronomers. The mechanism of the universe was known before Harvey discovered the circulation of the blood, or Watt constructed a steam engine. The astronomers seem to have been the pioneers of every branch of human knowledge. The Old and the New Testament open astronomically: "In the beginning God created the heaven and the earth" (Gen., i., I). "The wise men from the east came to Jerusalem, saying, where is He that is born King of Jews? for we have seen His star in the east" (Matt., ii., 2). It must be remembered that the science of astronomy in one important respect differs from all other sciences. Astronomers are observers only - they ascertain causes by watching effects. They cannot interfere with or alter the causes in operation.

If astronomy has taught man anything it is the painful fact that we are not special creatures in any sense of the term. Our star is an average one, and the conditions that led to the formation of our planet and ourselves were probably not very extraordinary.

Astronomers are experts on understanding what light is. We can’t touch or sense most of the objects that we study, other than from the light that we receive from them.