Across the galaxy, astronomers now see that planetary systems fall into four broad classes, and our own solar system, part of the rare Ordered group, is only one of them. At the same time, discoveries ...

For a decade and a half, astronomers have been on the trail of a galactic mystery. In 2011, a project that surveyed the Milky Way galaxy for exoplanets — which are planets beyond our solar system — ...

The official number of exoplanets—planets outside our solar system—tracked by NASA has reached 6,000. Confirmed planets are added to the count on a rolling basis by scientists from around the world, ...

Orbiting a small, cool M dwarf star once every 4,170 days, the planet's location is remarkable — it is only the third planet in the entire history of space observation to be discovered so far away ...

For centuries our solar system was the only planetary system known to humans. We had no proof other worlds existed beyond those in our own cosmic backyard, and we imagined that if other planetary ...