How many dwarf planets are there in our solar system? The recent discovery of 2017 OF201 makes the tally anywhere between ...

If Planet Nine is finally discovered, as one of those who first postulated its existence, does Brown have any suggestions for a possible formal name for this new member of the solar system?

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

And could humans ever make the trip? Planet Nine is the name given to a proposed planet supposedly lurking near the edge of the solar system.

Computer simulations show that planets could be flung out of the inner solar system, supporting the possible existence of a ...

An elusive Earth-like planet in our solar system could finally be discovered within the next few years. Known as Planet Nine or Planet X, it is a hypothetical planet that has long been rumoured to ...

Artist's impression of Planet Nine – a suspected “wide-orbit” planet – with the Sun in the distance; Neptune's orbit is shown ...

Though Pluto has formally been considered a dwarf planet for almost two decades, it still has many lessons left for planetary scientists — including hints about how the solar system formed.

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it.

Planet Nine is the name given to a proposed planet supposedly lurking near the edge of the solar system. If it exists, Planet Nine is likely a dark, gas or ice giant planet somewhere between five ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.