Compare the Planets
The worlds of our solar system come in all shapes, sizes, and colors. Red-eyed Jupiter, ringed Saturn, and frigid Uranus and Neptune are giant gassy globes containing nearly all of the matter in the solar system. These Jovian planets, or gas giants, are huge worlds of air, clouds, and fluid that may have no solid surfaces no matter how deep you go.
Everything else in the solar system is just rock, ice, and dust. The largest rockballs are known as the terrestrial planets: Mercury, Venus, Earth, and Mars. Earth is the biggest of all the rocky worlds. But the planets are not the only worlds of the solar system. All but two of the planets are orbited by moons, each of them a world unto itself. The largest moons are bigger than the smallest planets.
What's biggest and smallest? Hottest and coldest? Which other place is most like Earth? And how many moons are there in the solar system anyway? Comparing each of the planets to each other helps us understand these worlds -- and the place of our own world, Earth, in the solar system.
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