Across
- 8. orbit the ___: a criterion to be a planet
- 10. a.k.a. terrestrial planet
- 12. terrestrial planets have ___ (3 words) moons
- 13. ____ isotopes: this is one reason for Earth's hot interior
- 14. a comet's tail points __ from the sun
- 15. a sphere around the solar system where comets exist
- 16. in order to be a planet, an object must clear its orbit of __
- 18. a.k.a. Jovian planet
- 20. all Jovian planets have them around them
Down
- 1. a.k.a. the habitable zone where water can be liquid
- 2. unable to clear its orbit, e.g. Pluto
- 3. one of the inactive planets
- 4. this is where many comets are located
- 5. potato-shaped object of rock and metal
- 6. process that stabilizes an atmosphere
- 7. ice, rock, and metal form this small solar-system object
- 9. where most asteroids are
- 10. medium and large moons are shaped like this
- 11. this process makes the inside of Io volcanically active
- 17. Jovian planets have ___ orbital periods
- 19. main component of Jovian planets (state of matter)