Els q4

4. A habitable zone is a shell-shape region of space surrounding a star where the temperature is just right (not too hot nor too cold) that it could maintain liquid water on its surface.
6. Mass must be large enough to retain the atmosphere and have a molten core that serves as a heat engine driving the geological processes.
7. The planets were formed by the collision of the sun with a giantcomet.
8. Detected between the lower mantle and the outer core as observed by changes in the seismic waves.
10. Separates the upper mantle from Earth’s crust.
11. Presence of heavier elements (metals) that the star contains.
13. Hypothesis is about angular momentum of the sun.
14. The planets should have elements most vital to life.

1. The planets were formed from the substance that was torn outof the sun.
2. Separating the outer and inner core is a seismic boundary sometimes referred to as.
3. Must be atleast 3 Ga old to give life an ample time to evolve.
5. Nebula collapses because of gravitational force, and contracts as it spins more rapidly.
9. Solar System was formed into bodies with nearly circular orbitsbecause of the whirlpool-like motion in the pre-solar materials.
12. Outermost layer of the earth.
15. Takes up the largest portion of Earth.