| A | B |
|---|
| big bang | a theory for the origin of the universe: explosion of concentrated matter and energy followed by continued expansion |
| heliocentric | how Copernicus described our solar system |
| geocentric | how Ptolemy described our solar system |
| solar systems | contain one or more stars, comets, asteroids, planets, and moons |
| comet | mountain-sized chunk of ice, dust, and rock in orbit around a star |
| asteroid | small, rocky body orbiting a star |
| meteoroid | chunk of a comet or asteroid in space |
| meteor | a meteoroid that enters the Earth's atmosphere |
| meteorite | a meteor that hits the Earth's surface |
| stars | spinning clouds of gasses that radiate heat and light |
| nuclear fusion | star's main source of energy, the combining or fusing of the nuclei of lighter molecules to form heavier elements producing energy |
| hydrogen to helium | an example of a nuclear fusion reaction |
| sun | a medium-sized star |
| spectrum | the wavelengths of light energy coming from a star that helps us determine its temperature and composition |
| constellation | a collection of stars with a distinctive pattern |
