Our Solar System has eight planets, a few dwarf planets and more than 200 moons. But wait. Are you seeing double? Or did every planet suddenly get a twin? Where would each planet’s double fit in? Why ...

Mercury is the innermost and smallest of the eight major planets in our Solar System, orbiting closest to the Sun. Though ...

Turn your attention to the nearby sky: to the 8 planets, 288 moons, and countless smaller rocky objects whose precarious existence began with, depends upon, and may end with the Sun. Last month, we ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

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 ...

New high-contrast images from SPHERE show a stunning variety of debris disks shaped by collisions of tiny planet-building ...

SPHERE’s detailed images of dusty rings around young stars offer a rare glimpse into the hidden machinery of planet formation ...

Still, science being science, we needed proof—and we got it in 1992, when two astronomers found two planets orbiting a pulsar ...