Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

Astronomers have picked up evidence of an Earth-sized world, distinct from the previously hypothesised Planet Nine and Planet ...

If Planet Nine is found, it would be the first such discovery since Neptune in 1846 and would mark a monumental shift in our understanding of how the solar system formed and evolved.

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

Scientists have thought that our solar system's inner rocky planets — Mercury, Venus, Earth and Mars —formed first (around 4.566 billion years ago), while gas giants and icy bodies in the ...

For a few evenings around 28 February, every planet in the solar system will be visible in the night sky, thanks to a rare great planetary alignment. Here's how to make sure you don't miss this ...

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.

This process, called accretion, is how everything in the solar system – planets, moons, comets and asteroids – came into being. Telescopes can see young solar systems being born.

A newly discovered object called 2017 OF201, likely a dwarf planet, travels in an extremely wide elliptical orbit (yellow), a new study suggests. The orbit of the dwarf planets Sedna and Pluto are ...

If our species manages to hang on for a few billion additional years, we might be in for a wild ride — stars passing in the vicinity of the sun could cause planets in our solar system to collide ...