A fresh study of the Kuiper Belt’s structure has revived that far-out question, pointing to a possible Earth-sized ...

To picture this, if Earth is one “Sun-step” away, Planet Y is about 100 to 200 “Sun-steps” out in the dark, distant part of our Solar System. That region lies far beyond Pluto, where sunlight barely ...

Using the James Webb Space Telescope, scientists have detected gas on the distant dwarf planet, Makemake. - NASA / ESA / Southwest Research Institute / A. Parker illustration Scientists have detected ...

Our solar system now, once again, officially consists of only eight planets. Although largely debunked, speculation continued ...

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 ...

Planet Y is the latest in a series of hypothetical solar system planets that scientists have proposed in recent years, all with slightly different characteristics, but collectively believed to be ...

A recent research paper suggests that a planet may exist far beyond Neptune — less than 20 years after the previous ninth planet, Pluto, was demoted. That research paper, accepted last month for ...

A dwarf planet nicknamed the Goblin has been discovered beyond Pluto, astronomers said Tuesday. Scott Sheppard of the Carnegie Institution for Science, one of the scientists who made the find, said ...

Scientists have detected methane gas glowing faintly above Makemake, an icy dwarf planet smaller and farther than Pluto in space. Until now, Pluto was the only object that far out in the solar system ...

(CNN) — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have ...