Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

Scientists examined infrared space surveys to narrow down candidates for Planet 9. Planet 9 would be so far from the Sun that it is just not illuminated by much sunlight. The two space surveys, ...

Astronomers believe there is a Planet Nine in the outer solar system beyond Neptune. A team led by Amos Chen from the National Tsing Hua University, is searching for Planet Nine’s heat signature. When ...