Over the last 20 years, we have discovered all kinds of strange planets we never thought could exist and that have no analog in our solar system. A whole new category of planets, Super Earths are quite common in our galaxy. These planets can be up to 10 times more massive than Earth. We don’t yet know enough about these planets to tell at what point they lose a rocky surface. But in the range of 3 – 10 times the mass of Earth, there might be a wide variety of planetary compositions, including water worlds, snowball planets, or planets that, like Neptune, are composed largely of dense gas.