Planetary Mysteries

Within the vast universe, the solar system is the Earth's little neighborhood. So it makes sense that scientists know more about the solar system than any other part of the universe. We know that ...

Some planets like the Earth and Venus are made of rock.
Other planets like Neptune and Uranus are mostly made of gas.
Saturn has at least 30 moons, while Mercury and Venus have none.
We've learned so much about the planets in our solar system. But there are still many mind-boggling mysteries.

We know all this because scientists around the world are investigating the solar system. They use information and pictures gathered by NASA and other space agencies. NASA observes the planets with telescopes, on land and in space. It sends spacecraft across the solar system. It even lands rovers on other planets.