Earth and Space Science / Unit 9: The Solar System
9.3 The Planets
Notes
| Group | Planets | Features |
|---|---|---|
| Terrestrial | Mercury, Venus, Earth, Mars | Small, rocky, dense, few moons |
| Gas giants | Jupiter, Saturn | Mostly hydrogen and helium, huge, rings |
| Ice giants | Uranus, Neptune | Water, ammonia, methane ices; cold |
- Venus is the hottest planet (about 465°C) because of its thick CO₂ atmosphere, not because it is closest.
- Mars is cold and dry with thin atmosphere; Jupiter has the Great Red Spot, a giant storm.
- Planet: orbits a star, is round, and has cleared its orbit. Pluto is a dwarf planet.
- Kepler's third law idea: planets farther out take longer to orbit.
Practice
Which planet is the hottest?
Venus has a runaway greenhouse effect.
Which planets are terrestrial?
Terrestrial planets are small and rocky.
Pluto is classified as a dwarf planet because it:
That is the criterion set in 2006.
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