If Planet 9 is real, this observatory has around a 70 to 80 percent chance of finding it, he estimates, adding that it's not a sure thing because there are so many uncertainties.

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.

A possible new dwarf planet has been discovered at the edge of our solar system, so far-flung that it takes around 25,000 years to complete one orbit around the sun. The object, known as 2017 ...

New Horizons spacecraft survives trip 1 billion miles beyond Pluto 02:03. It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

Curiosity Mars rover turns 10 04:00. NASA's Curiosity rover has captured the first close-up images of a part of Mars that scientists say provide evidence of how water once flowed on the red planet ...

The hunt for Planet Nine—the solar system’s ghostly gravitational troll—is longstanding, and is based on the peculiar clustering of rocky bodies in the Kuiper Belt beyond the orbit of Neptune.

Earth has a newly-discovered neighbor in the solar system.. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

An artist’s impression of K2-18 b. Researchers report finding a signature of life’s activity in the planet’s atmosphere. Credit: ESA/Hubble, M. Kornmesser ...