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The Solar System
Planets
A tour from the Sun outward
1
Mercury
Closest to the Sun; small, rocky, and heavily cratered.
- Orbital period: ~88 Earth days
- No atmosphere to speak of
2
Venus
Similar in size to Earth; thick CO₂ atmosphere, runaway greenhouse.
- Extremely hot surface
- Rotates slowly in the opposite direction
3
Earth
Our home: liquid water, life, and a protective atmosphere.
- One natural satellite: the Moon
- Orbital period: ~365 days
4
Mars
The Red Planet; thin atmosphere, ancient riverbeds, and polar ice.
- Two moons: Phobos and Deimos
- Target for robotic and future human exploration
5
Jupiter
Largest planet; gas giant with a famous Great Red Spot.
- Dozens of moons, including Europa and Ganymede
- Mostly hydrogen and helium
6
Saturn
Gas giant with spectacular rings made of ice and rock.
- Many moons; Titan has a thick atmosphere
- Less dense than water
7
Uranus & Neptune
Ice giants: cold, blue, and rich in ices (water, ammonia, methane).
- Uranus: tilted on its side
- Neptune: strong winds and dark storms