Terrestrial Planets

3. The process by which hydrogen is converted to helium in the core of a star
5. The largest mountain in the solar system
6. the classification given to the four innermost planets composed mostly of metals and silicate rocks
7. The classification given to the four outermost planets which retained large amounts of hydrogen, helium, and other light elements in gas form
8. the largest plain, crowned by the largest mountain on Mars
10. term used to describe venusian tectonics because it is dominated by the rising and sinking of its mantle and crust
12. source of the Earth's internal energy based on unstable isotopes

1. plate boundary where oceanic crust descends beneath a plate with thicker crust
2. area under the rocky layer of crust where magma is hotter than surrounding magma
4. A stream of charged particles radiating outward from the sun at high speed
9. The speed a particle needs to reach to leave a planet's gravity
11. The giant canyon on Mars approximately 10 times longer and six times wider than the Grand Canyon
13. The coming together and cohesion of matter under the influence of gravitation to form larger bodies