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 ...

With the exception of Pluto, planets in our solar system are classified as either terrestrial (Earth-like) or Jovian (Jupiter-like) planets. Terrestrial planets include Mercury, Venus, Earth ...

This could suggest that the ninth planet he thought he discovered isn’t real. He also recommended ... gravitationally perturbing the distant solar system in the ways that we have suggested.

You may need binoculars or a telescope for this one. It includes the three furthest planets in our solar system. There will be six planets visible this time around, including Venus, Mars ...

Other researchers, such as Konstantin Batygin and Michael Brown, argue that an unseen planet several times larger than Earth could be "shepherding" smaller objects in the solar system. Batygin and ...

If planet X exists, it is likely a gas giant similar to Neptune. NASA/Caltech/R. Hurt (IPAC), CC BY Our solar system is a particularly crowded place. Millions of objects move within it, whether they ...