Earth has a nearly circular orbit, but some planets outside our solar system, called exoplanets ... Large planets need metal-rich stars in order to form; small planets do not.

With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, and it's the only one known for sure to have liquid water on its surface. Earth is also unique in terms of ...

Everyone knows about the Solar System, and the planets that make it up. They’re in space, orbiting the Sun, in an order we all at least used to be able to recite. But it was not always so.

The two exoplanets, or planets outside of our solar system, orbit a star called TOI-1453, which is slightly cooler and ...