Astronomy definitions

Astronomy
The branch of physics that studies celestial bodies and the universe as a whole

Light year
The distance which a ray of light would travel in one year. This is about 6,000,000,000,000 (6 trillion) miles.

Constellation
Any of the 88 various groups of stars to which definite names have been given.

Asteroid
Any of the thousands of small bodies that revolve about the sun in orbits lying mostly between those of Mars and Jupiter

Corona
The outermost part of the suns atmosphere 

Galaxy
A group of stars, gas and dust held together by gravity.

Satellite
A small object orbiting a larger one. There are many electronic objects that orbit the Earth.

Revolve
When something is moving in a circle around another object such as the way the Moon Circles the Earth it is said to revolve around that object.

Rotate
When an object spins it is said to be rotating.

Planet
An object moving around a star

Milky Way
The galaxy in which we live.

Meteor
A shooting star, observed when a particle of dust enters into the Earth's atmosphere.

Meteorite
An object from Outer Space such as a rock, that falls into the earth, and lands on its surface.

Eclipse
When our view of one object in the sky is blocked by either another object, or the Earths shadow.

Comet/Coma
A small, frozen mass of dust and gas revolving around the sun.

Aurora
Beautiful lights seen over the Polar Regions which are caused when energized particles from the Sun react with the Earths magnetic field.

Umbra
The dark inner part of a sunspot, or shadow.

Penumbra
The lighter part of a shadow found on the shadows edge.

Solar system
The system of planets and other objects orbiting the star , which happens to be our Sun.

Star
A self-luminous object that shines through the release of energy produced by nuclear reactions at its core.

Supernova
A super bright explosion of a star. A supernova can produce the same amount of energy in one second, as an entire galaxy.

Orbit
The path one object takes around another.

Equator
An imaginary band which circles the earth at its widest point.

Axis
An imaginary straight line on which an object rotates.

Telescope
An instrument used for viewing far away objects