Astron (Greek: ἄστρον, romanized: ástron) is the branch of physics that studies astronomical objects and phenomena. It applies the laws of physics to the study of the Sun, planets, stars, galaxies, and the Universe as a whole. Astronomy is one of the oldest sciences. The early astronomers were able to make fairly accurate predictions about heavenly motions using simple mathematics. Today, astronomy is a highly precise science that makes use of increasingly sophisticated instruments and techniques.
The word “astron” comes from the Greek word for “star”, astron (ἄστρον). In ancient times, astronomy was primarily concerned with tracking the movements of objects in the night sky so as to be able to predict their positions at future dates. This allowed for things such as navigation by the stars and predicting eclipses. Modern astronomy is much more diverse, however; it covers all aspects of stellar astrophysics (the study of stars), extragalactic astrophysics (the study of galaxies beyond our own Milky Way), cosmology (the study of the large-scale structure and evolution of the Universe), planetary science (the study of planets both inside and outside our Solar System), solar physics (the study of our own Sun), and astrobiology (the study of life in space). Much recent astronomical research has been focused on understanding dark matter and dark energy, which are thought to make up most of the mass/energy in the Universe but whose properties remain largely mysterious.
There are several different types of telescopes that astronomers use to observe different parts of the electromagnetic spectrum, from radio waves to gamma rays. The field has also made significant advances through theoretical work done using computer simulations. Numerical simulations have become an essential tool in testing theories against observations—for example, they have been used extensively in studying how galaxies form and evolve over time.
Astronomers use a variety o