Astronomy is the science that deals with the sun, the moon, the planets, the stars and all the other heavenly bodies like supernova, comets and galaxies. Astronomy is the oldest science of all. It was done at least 5000 years ago by the Babylonians, as well as by the Megalithic peoples who lived in Britain and Ireland, like those who built Stonehenge about 4000 years ago. Originally astronomy was only about the theory of the movement and position of heavenly bodies in the sky. Mostly what astronomers did was measure the positions of the stars and planets very precisely and then try to work out theories to predict their movements. However, in the 17th century people started to get interested in other characteristics of the sun, moon and planets, such as what they were made of, whether they had mountains on them, whether they changed their appearance and why. Nowadays astronomy has many sub-branches, like X-ray astronomy, radio astronomy and astrophysics.

Maths has always been extremely important in astronomy. In fact, astronomy was the subject that used maths by far the most until quite recently. In medieval times astronomy was one of the four sciences of the 'quadrivium' which was taught in universities. All the great astronomers have also been great mathematicians: Galileo, Tycho Brahe, Christopher Wren, Ptolemy, Kepler, Copernicus, and Newton for example.