If the object really is Planet Nine, it would be larger than Neptune and exist 700 times further from the sun than Earth.

A new look through decades-old data has unveiled some of the most compelling evidence yet of a hidden ninth planet in the far ...

Using two infrared space telescopes and a 23-year gap, scientists may have spotted a mysterious, slow-moving object beyond ...

For over a century, astronomers have wondered if there's an extra planet in our Solar System that we haven't been able to see ...

The presence of another planet in the solar system could explain the odd movements of some of the bodies in the Kuiper Belt.

The solar system consists of our star, the sun, and everything bound to it by gravity: the planets Mercury, Venus, Earth, ...

While scientists are still trying to confirm Planet Nine's existence, NASA says proving that this ice giant is real would help astronomers explain several mysteries within our solar system.

Jupiter is the largest planet in the solar system. It's about 11 times wider than Earth with an equatorial diameter of 88,846 ...

Pluto was discovered in 1930 in Arizona, but in 2006 scientists decided to cut Pluto from the planetary line up. Here is why ...

BD+05 4868 Ab is located about 140 light years away from Earth and has a surface temperature of 1,600 deg C. Read more at ...