Across
- 3. a portion of a meteor that survives passage through an atmosphere and strikes the ground
- 6. a stony or metallic object orbiting sun
- 7. time required for half the radioactive atoms in a simple to disintegrate
- 9. objects, from tens to hundreds of kilometers in diameter, that formed in the solar nebula as an intermediate step between tiny grains and the larger planetary objects we see today
- 10. of the planets Mercury, Venus, Earth, or Mars; sometimes the Moon is included in the list
- 11. gravitational separation of materials of different density
Down
- 1. the cloud of gas and dust from which the solar system formed
- 2. a small piece of solid matter that enters Earth’s atmosphere and burns up, popularly called a shooting star because it is seen as a small flash of light
- 4. process by which certain kinds of atomic nuclei decay naturally, with the spontaneous emission of subatomic particles and gamma rays
- 5. any of the planets Jupiter, Saturn, Uranus, and Neptune in our solar system
- 8. small body of icy and dusty matter that revolves around the sun