Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

At the center is the sun, a yellow dwarf star that contains 99.8% of the solar system's mass. Everything else — from the eight major planets to dwarf planets, comets, asteroids, and icy objects ...

Warmer climates than Earth’s could accelerate life’s development, potentially increasing the number of planets with more ...

Earth has four seasons, but do other planets in our solar system also have hot summer days and cold winter nights?

Astronomers have detected a promising sign of a ninth planet lurking at the the farthest reaches of the Solar System.

Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner ...

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

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

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

Discovered in 1930, Pluto was long considered our Solar System's ninth planet, but was unseated in 2006 after the discovery ...

Astronomers may have found a candidate for Planet Nine. This planet is beyond Neptune. The finding could be the first ...

Our solar system may have a ninth planet after all, researchers say ... an unusual clustering of icy bodies -- including comets and dwarf planets -- which stretches from Neptune and outward ...