Astronomy Concepts

Front

Astronomical unit (A.U)

Back

The average distance from our Sun to the Earth. Astronomical units are typically used when describing distances in our solar system.

Front

Big Bang

Back

The origin of the universe where the observable universe expanded rapidly from a single point.

Front

Black hole

Back

An object that has gravity so strong that even light can't escape it. Black holes form in supernova explosions of stars with more than 20 times the mass of the Sun.

Front

Cosmic microwave background radiation (C.M.B.R)

Back

Long wavelength radiation left over from the Big Bang. C.M.B.R is spread evenly throughout the universe and is evidence for the Big Bang.

Front

Doppler effect

Back

The change in wave frequency during the relative motion between a wave source and its observer.

Front

Galaxy

Back

A group of millions or billions of stars held together by gravity.

Front

Large star

Back

A star with more than 8 times the mass of the Sun. A large star becomes a red supergiant and explodes in a supernova, leaving behind either a black hole or neutron star.

Front

Light-year

Back

A unit of length equal to the distance light travels in one year.

Front

Main sequence star

Back

A star that is fusing hydrogen and in a stable state. Main sequence stars are stable because the outward force of fusion is balanced by the inward force of gravity.

Front

Milky Way

Back

The galaxy in which the Solar System is located. The Milky Way galaxy contains about 100 billion stars.