The planets are in a star-forming region relatively close to our Sun in the southern constellations of Upper Scorpius and Ophiuchus. Although there may be billions of these rogues out there in the Milky Way, the 170 scientists found in this section of the galaxy represents the largest group of rogue planets discovered to date.

"We did not know how many to expect and are excited to have found so many," says study first author Dr. Nuria Miret-Roig of Bordeaux University in a media release.

Rogue planets are a bit of a mystery to astronomers. For comparison, our Sun has at least eight planets orbiting it (nine if you count Pluto). From what scientists can tell, most other stars also have planets circling them as well.

Planets 'glowing' in the dark

An international team combined observations from space and ground-based telescopes to spot the rogues. Since these mysterious worlds float far away from any star that could illuminate them, it would normally be impossible to image. However, even in the few million years after their formation, they are still hot enough to glow.