Space

4. the regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms
6. technique used to date materials such as rocks or carbon
8. an element subject to spontaneous degeneration of its nucleus accompanied by the emission of alpha particles, beta particles, or gamma rays
9. the theory that the solar and stellar systems were developed from a primeval nebula
10. defined as metals with relatively high densities, atomic weights, or atomic numbers
11. the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets

1. a celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun
2. a large planet of relatively low density consisting predominantly of hydrogen and helium
3. a planet that is composed primarily of silicate rocks or metals
5. the continuous flow of charged particles from the sun that permeates the solar system
7. a small rocky body orbiting the sun