A new study suggests yet another theory for a possible extra planet in our solar system, likely of a size between Mercury and ...

Our solar system is a smashing success. A new study suggests that from its earliest period—even before the last of its ...

The solar system is a grand cosmic stage where each planet and moon plays a unique role in a story billions of years in the making. From Mercury’s shrinking surface and Venus’s runaway greenhouse ...

Voyager 1 has been exploring the cosmos for decades, but when it reached the edge of the solar system, it found something ...

Astronomers have discovered fresh evidence suggesting the possible existence of an unseen planet in the far reaches of our ...

Astronomers have discovered new evidence that suggests the possibility of an unknown planet in our solar system's farthest ...

While Planet Y has been not yet been directly observed, unexpected inclinations found in the orbits of roughly 50 distant ...

Astronomers have discovered a significant “growth spurt” in a rogue planet outside of our solar system. The free-floating ...

"It was just a matter of time before we found them." ...

I recall as a child lying on the grass at night, gazing up at the stars, and wondering if any of those distant suns had planets orbiting nearby. I was not ...