An all-sky picture of the infant universe revealing 13.77 billion-year-old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies. (Credit: NASA/WMAP Science Team)
Astrophysics is a branch of astronomy that explores the physical properties of the cosmos and its composition. Astrophysicists study a broad range of topics, from the tiniest particles of matter and the forces that join them together to the grandest of celestial structures. In essence, astrophysics extends the workings of physics and chemistry that we experience directly here on Earth into the vastness of space. It is both an observational and theoretical science. To probe the universe's past, present and future, astrophysicists have built some of the most complex and precise machines in the world, including terrestrial and space-based telescopes tuned to various wavelengths. The continued seeking of new discoveries is constantly pushing the limits of telescope and model-building technology.