Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, researchers say. ABC News. Video. Live. Shows. Shop. Log In. Stream on.

In an exciting breakthrough in planetary science, a recent study has increased the likelihood of Planet Nine’s existence by up to 40%. This planet, also referred to as Planet X, has remained an ...

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 ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory ...

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

A MYSTERIOUS cosmic object has been spotted zooming through our solar system – and astronomers say it is only the third of ...

Close stellar encounters could change the structure of our planetary system, potentially dooming Earth or other worlds to ...

For the dwarf planet candidate, one trip around the sun takes over 24,000 years. Its orbit challenges a proposed path for a hypothetical Planet Nine.

I/ATLAS, earlier known as A11pI3Z, is only the third interstellar visitor to be discovered passing through our corner of the ...

The James Webb Space Telescope has observed two large planets at different stages of infancy - one with an atmosphere brimming with dusty clouds and the other encircled by a disk of material - ...

But an international team of astronomers have detected the unmistakable signature of a gas giant planet orbiting the ...

Astronomers on Wednesday confirmed the discovery of an interstellar object racing through our Solar System -- only the third ...