Astronomy Terms

Astronomy terms are used to describe the various phenomena in space. In this section you can learn what every astronomy term means and how it helps us to better understand the cosmos.


Quasar, or Quasi-stellar Object (QSO), a starlike object displaying an unusually large red shift.

Andromeda Galaxy, a spiral galaxy that is larger than the Milky Way (the galaxy to which Earth belongs) but similar to it in structure, and the closest to ours.

Eros, a small asteroid (minor planet) discovered in 1898. It was the first asteroid known to come closer to the earth than the planet Mars.

Astrogeology, the science that applies the principles of geology to the study of solid bodies of the solar system other than the earth.

Transit, in astronomy, the passage of one celestial body across the disc (face) of a larger, more distant body, or across the observer's meridian.

Astrophysics, the application of the theories and techniques of modern physics to astronomy.

Autumn, or Fall, the season of the year that follows summer and comes before winter.

Azimuth, the horizontal direction of an object, measured clockwise in degrees, minutes, and seconds of arc from true north or south along the theoretical horizon.

Bolometer, an instrument used to measure infrared, or heat, radiation. The bolometer is essentially a very sensitive thermometer.

Brown Dwarf, a celestial object more massive than a planet but less massive than a star.

Chronology, the science of measuring time. Chronology divides time into regular divisions or periods, and assigns events their proper place and sequence by giving them dates.