| A | B |
|---|
| universe | everything in space |
| astronomer | a scientist who studies the universe |
| refracting telescope | a telescope that gathers light with a lens |
| reflecting telescope | a telescope that uses mirrors to gather light |
| observatory | a place where astronomers study the sky |
| radio telescope | a telescope that gathers radio waves from objects in space |
| satellite | an object that circles another object in space |
| space probe | an unmanned craft sent out into space; space probes do not orbit planets |
| astronomical unit | a unit of measure equal to the average distance between Earth and the sun |
| light year | the distance light travels in one year |
| constellation | a group of stars named for an object, person, or animal |
| galaxy | a group of stars, dust, and gases held together by gravity |
| magnitude | a way to measure the brightness of a star |
