An astronomer is a person who studies everything above Earth’s atmosphere.

The field of astronomy is so broad that no one person can hope to be fluent in all aspects. Most astronomers specialize in one of several branches of astronomy. Astrophysicists study the origin and evolution of stars. Planetary geologists study the formation of planets. Cosmologists study the origin, evolution, and ultimate fate of the universe.

Astronomers rarely have the opportunity to study astronomical objects directly. They must depend on various forms of electromagnetic radiation received from distant objects. However, much information can be extracted from the radiation through careful analysis: chemical composition, temperature, motion through space, rotation speed, magnetic field strength, and other physical features.

In order to measure how bright an object in space is or measure its actual size, the distance to the object must be determined accurately. For example, a star could be bright because it is intrinsically a bright star, or it could be bright because it is very close. However, distance is one of the most difficult things to measure. To determine distances in space, astronomers depend on triangles.

Astronomers also use triangles to determine the distance to nearby stars.

As Earth goes around the Sun, nearby stars shift their angular position by a small amount against the background of more distant stars. This angle,  called a “parallax,” can be measured accurately by astronomers. It is the vertex angle of a long isosceles triangle whose base is the diameter of Earth’s orbit. Thus, using simple trigonometry, astronomers can determine the height of the triangle and thus the distance to the star.

Astronomers typically work at universities that own and operate major telescopes. To work in astronomy at this level, a doctorate is required along with several years of post-doctorate work. Astronomers in training take many courses in physics, engineering, computer science, and basic astronomy.

Since working in astronomy requires an understanding of both quantum mechanics and general relativity, the mathematics requirements are difficult. Astronomers take many courses in advanced mathematics.

There are very few jobs for astronomers. Even jobs as astronomical technicians are hard to get and are usually reserved for advanced graduate students in the field. However, astronomy is one of the very few scientific disciplines where amateurs can make a significant contribution. Astronomers observe double stars, variable stars, search for asteroids, and search for comets. There are official channels where the information collected by amateurs can be transferred to scientists. 

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Reference

Chaisson, Eric, and Steve McMillan. Astronomy Today, 3rd ed. Upper Saddle River, NJ: Prentice Hall, 1993.