When most people think of our Solar System, they think of the 8 planets officially recognized by the International Astronomical Union (IAU). But what if I told you there are at least 40 planets, and ...

A new interstellar object, A11pl3Z, has been discovered in our solar system, marking the third such object to be observed. It ...

Rocky bodies called protoplanets were thought to have formed slightly earlier in the inner solar system than those beyond the ...

The location of the solar system's outer boundary is a point of contention among astronomers. There are three possible candidates, which "all have merit." But which one is best?

The solar system has many more moons than the one we can see in the sky. But how many do we actually know about? And how many more are waiting to be discovered?

The International Astronomical Union defines a planet as a celestial body that orbits the sun, is massive enough that gravity has forced it into a spherical shape, and has cleared away other objects ...

All eight of the solar system’s “major” planets appear in this illustration, but the actual number of planetary bodies orbiting our star is far greater.

Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, researchers say.

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.

The Sun is orbited by eight planets, at least five dwarf planets, tens of thousands of asteroids, and around three trillion comets and icy bodies. Although not all objects of the solar system are ...

The proposed new definition contains quantifiable criteria that can be applied for defining planets inside and outside our solar system. In the new definition, a planet is a celestial body that: ...