Are there differences among the planets in our solar system?

Planets come in different sizes, compositions and colors. The four planets closer to the Sun are called "rocky" planets. They are small in size and similar to Earth in composition. They have no rings and only two of them (Earth and Mars) have moons.

The four outer planets, also called "gas giants," are much larger than the rocky planets. They all have rings and have many moons. The gas giants are made up mostly of hydrogen, helium, frozen water, ammonia, methane and carbon monoxide.

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