A theory which states that the Universe began to expand after a super powerful explosion of concentrated matter and energy.

The layers of gases which surround a star, like our Sun, or a planet, like our Earth.

Frozen masses of gas and dust which have a definite orbit through the solar system.

A path around an object which decreases in size with time. For example, when a satellite enters a decaying orbit above Earth, its orbit size decreases to the point that it enters Earth's atmosphe [..]

An educational institution which has been recognized as maintaining standards that qualify graduates for admission to higher, or more specialized, institutions or professional practice.

A rocky space object which can be from a few hundred feet to several hundred km wide. Most asteroids in our solar system orbit the Sun in a belt between Mars and Jupiter.

An expert in the study of the Sun, Moon, stars, planets, and other space bodies.

The approximate distance from the Sun to the Earth which is equal to 150,000,000 kilometers.

The branch of astronomy that deals with the physics of stellar phenomena.

An imaginary straight line around which an object rotates.