Term | Definition |
Light Year | The distance that light can travel in a year. |
Astronomical Unit (AU) | The distance from the Earth to the Sun |
Relative Size | Objects that are closer appear larger
Objects that are farther away appear smaller. |
Universe | All of space and everything in it |
Galaxy | A huge system of stars, star systems, dust, and gas held together by gravity. |
Nebula | A large cloud of gas and dust in space
New stars can form inside |
Solar System (Star System) | A star and all of the planets and other objects that revolve around it. |
Planet | A round object that orbits a star and has cleared the area of its orbit.
Can be rocky or gas. |
Dwarf Planet | A round object that orbits a star, but has NOT cleared the area of its orbit. |
Moon | An object that orbits a planet. |
Comet | Small body of ice, rock, & dust that orbits the sun.
Has a “tail” because the sun’s heat melts ice, & creates gas |
Asteroid | Large rocky object that orbits the sun, usually found between Mars & Jupiter. |
Meteor | Piece of rock that travels through space, and burns up as it enters Earth's atmosphere, making a "shooting star". |
Weight | The amount of gravity pulling on an object (changes) |
Mass | The amount of matter in an object (doesn’t change) |