Definitions of heavenly bodies

Asteroid – Asteroids are bodies of rock and ice in space. Millions of asteroids orbit the Sun -most between Mars and Jupiter. They vary in size between 1 metre across and 600 miles across.
Atmosphere – the layer of gas around a planet
Comet – a comet is a body of ice, dust and bits of rock that passes through space leaving a tail of ice and dust behind it. A comet may be up to 25 miles across.
Day – the length of time it takes the Earth to spin all the way around so that you get a night and a day – 24 hours
Galaxy – a large group of stars, all orbiting a central point.
Gravity – the force that attracts a moon to a planet, or a planet to a star
Light Year – the distance that light travels in one year. 5.9 trillion miles
Meteor – a small piece of debris in space, up to the size of a boulder
Milky Way – the galaxy that we live in
Moon – A moon is a smaller object orbiting a planet. Some planets have many moons. Earth has just one, called The Moon.
Orbit – the path that a planet takes around the Sun, or that a moon takes around a planet
Planet – a large body of either rock or gas that follows a consistent orbit around a star
Shooting star – This isn’t really a star! A shooting star is a meteor that is passing through the Earth’s atmosphere and has got so hot that it glows in the night sky.
Solar System – the Sun and the collection of stars
Star – A star is a huge ball of very hot gases, that gives off lots of light and heat. Some stars have planets orbiting around them, but not all do.
Sun – the star in our Solar System
Universe – The Universe is everything that exists: all the galaxies, all the stars, all the planets and everything in between
Year – the length of time it takes the Earth to travel around the Sun, 365 days