Add Yahoo as a preferred source to see more of our stories on Google. Jupiter is already the biggest planet by far in our solar system, but new research suggests it was somehow once even larger than ...

This article was originally featured on The Conversation. 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 ...

Astronomers have discovered more than 300 exoplanetary systems that have three or more known planets. Most of these planets are about the same size and spaced close together, earning them the moniker ...

Our solar system may have a ninth planet after all, researchers say. The possibility that an additional planet may be hidden far into the solar system was touted more than a century ago. But ...

When you see art of our solar system as the planet orbit the sun, you may notice that Earth's orbit has a tilt. It is not a perfect circle. What's more, Earth is not the only planet that displays such ...

Venus and Saturn are due up for a visually striking event known as a planetary conjunction. Here's everything to know about ...

A planetary scientist and a young astronomer give tips on how to find the six planets that will be visible during the planet ...

For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, Pluto was officially reclassified as a dwarf planet by the International ...