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 ...

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

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 collapsing gas created our Sun, the first thing to form in ...

From lava worlds to gas giants, NASA says the variety of these worlds is staggering—and that signs of a further 8,000 distant ...

Exoplanet hunters Christopher Watson and Annelies Mortier explain the long search for a 'twin Earth' capable of sustaining ...

Astronomers have discovered the earliest seeds of rocky planets forming in the gas around a baby sun-like star, providing a precious peek into the dawn of our own solar system. It’s an unprecedented ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence ...

There’s a bit of a paradox about our galaxy: it’s both jam-packed with stars and cavernously empty. The Milky Way is crowded in the sense that it holds hundreds of billions of stars, as well as ...

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