| A | B |
|---|
| Solar System | The Sun and its family of orbiting planets, moons, and other objects. |
| Galaxy | Millions or billions of stars held together in a group by their own gravity. |
| Universe | Space and all the matter and energy in it. |
| Constellation | A group of stars that form a pattern in the sky. |
| Orbit | The path of an object in space as it moves around another object due to gravity; for example, the Moon moves in an orbit around Earth. |
| Orbit | To revolve around, or move in an orbit; for example, the Moon orbits Earth. |
| Electromagnetic radiation | Energy that travels across distances as certain types of waves |
| Wavelength | The distance from one wave crest to the next crest; the distance from any part of one wave to the identical part of the next wave. |
| Spectrum | Radiation from a source separated into a range of wavelengths. |
| Spectrum | The range of colors that appears in a beam of visible light when it passes through a prism. See also electromagnetic radiation. |
| Telescope | A device that gather visible light or another form of electromagnetic radiation. |
| Satellite | A body that orbits a more massive body. A natural satellite is also called a moon. |
| Space station | A satellite in which people can live and work for long periods. |
| Lander | A craft designed to land on a planet’s surface. |
| Probe | A spacecraft that is sent into a planet’s atmosphere or onto a solid surface. |
