Astronomy is the scientific study of the universe as a whole and of objects that exist naturally in space, such as the Moon, planets, stars, and galaxies. The Sun is a rather typical star moving around the center of the Milky Way at a distance of 20,000 light years. This Milky Way, our galaxy, is made of hundreds of millions of stars with vast empty regions and diffuse gas in between all held together by gravity. There are at least another hundred billion galaxies in the observable universe.

Every day and night astronomers collect data on these objects in all bands of the electromagnetic spectrum of light. From radio waves through X-rays, small and large telescopes on the ground and in space record immense amounts of data. Analyzing these data is one of the major challenges of modern astronomy. Sophisticated time-dependent, three-dimensional models of astronomical...