A surprising chemical difference between Pluto and Sedna, another dwarf planet in the distant Kuiper Belt, is helping scientists nail down their respective masses, a new study reports. "Kuiper Belt ...

Caltech astronomers have discovered the most distant known object in the solar system, a frigid, near-planet-sized body of rock and ice that is now three times as far from the sun as Pluto. The ...

Here’s what you’ll learn when you read this story: In 2076, the dwarf planet Sedna will make its closest approach to the Sun in 11,400 years, and scientists are now figuring out the best way to visit ...

In 2004, astronomers announced the discovery of a red, frigid planet-like body at the outskirts of our solar system. Michael E. Brown, the Caltech astronomer who spotted the object (and who would ...

LOS ANGELES - Peering into the far reaches of the solar system, astronomers have spied a pink frozen world 7.5 billion miles from the sun. It's the second such object to be discovered in a region of ...

Astronomers studying 35 NASA Hubble Space Telescope (HST) images of the solar system's farthest known object, unofficially named Sedna, are surprised the object does not appear to have a companion ...

While for most people Pluto is the most distant planet in the Solar System, things get a lot more fuzzy once you pass Neptune and enter the realm of trans-Neptunian objects (TNOs). Pluto is probably ...

Object 90377 Sedna — a distant trans-Neptunian object known best for its highly elliptical, 11,390-year-long orbit — is currently on its way towards perihelion (its closest approach to the Sun) in ...

The discovery of a nearly Pluto-sized object way out beyond the known worlds could jeopardize the status of Pluto as a planet, adding fresh fuel to an argument among astronomers that is likely to last ...

There could be a ninth planet in our solar system that's lying in wait to be discovered - and no, it's not Pluto. Our solar ...

Our corner of the galaxy got a little stranger this week with the discovery of Sedna, the most distant object ever spotted in the solar system. Now astronomers are puzzling over how it got there. The ...

While new discoveries about Mars continue to make headlines, another “red planet”—known as Sedna (or 90377 Sedna)—is making its way into the inner solar system. At this moment, the crimson-hued dwarf ...