Language/English/Vocabulary/Astronomy

Universe

Everything that exists in space.

Galaxy

A system of millions of stars.

Star

A star is a type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The sun is the star closest to our planet.

Solar System

Any collection of planets and their moons orbiting around a star; "Our Solar System" consists of eight planets (earth included), some of them with one ore more moons, planetoids, asteroids, and our sun.

Planet

A celestial body moving in an elliptical orbit around a star.

Moon

A natural satellite orbiting a planet.