Today, it’s believed that Jupiter and Saturn, the largest planets, were the first to fully form, both within a few million ...

A new dwarf planet, discovered beyond Neptune and described as Pluto's 'cousin,' could void the hypothesis of a Planet X in ...

A small team led by Sihao Cheng, Martin A. and Helen Chooljian Member in the Institute for Advanced Study's School of Natural ...

In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and ...

A recent study found that Jupiter was once twice the size that it is now, making it big enough to swallow up 2,000 Earths.

Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

A team of astronomers believe they may have discovered a new dwarf planet—just like Pluto—on the edge of our solar system.

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

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

For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, ...

Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky A cloud of collapsing gas created our Sun, the first thing to ...