A tiny object far beyond Pluto, newly discovered by the Subaru Telescope, could reshape our understanding of the early Solar ...

"It is possible that a planet once existed in the solar system but was later ejected, causing the unusual orbits we see today ...

But long before the Pluto “controversy,” other objects moved on and off the official list of solar system planets. Indeed, a kindergartener in the early 1800s would have learned that Ceres was ...

At the far reaches of our Solar System lies Pluto, a mysterious world shrouded in shadows and icy terrain. NASA’s latest photos from this distant dwarf planet have provided us with groundbreaking ...

Astronomers have hoped for the existence of Planet Nine for years. Things were looking promising, but this discovery might ...

Pluto has taken a special place in planetary scientist Alan Stern's mind since 1988. That's when he first began pushing NASA to send a spacecraft to what was then the ninth planet in our solar system.

Since 1930, we’ve discovered that Pluto is one of the solar system’s most fascinating worlds. It features blue skies, red snow, glaciers made of frozen nitrogen, and dunes made of frozen ...

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.

On February14, 1990, NASA's Voyager 1 probe pointed back toward the sun and took a seriesof pictures of the sun and the planets, making the first ever"portrait" of our solar system as seen from ...