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 ...

Scientists say they have found the first example of a new breed in the solar system's menagerie: a planetoid that spends all its time far beyond Pluto, in a chilly region that was once thought to be ...

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 ...

More than a decade after an oddball world named Sedna was discovered on the solar system's far frontier, a fresh discovery reveals that it's not so odd after all. Sedna and the newly found object, ...

Contrary to predictions, the most distant object known in the solar system doesn’t appear to have a moon. According to Hubble Space Telescope images released last week, the remote body dubbed Sedna ...

Sedna was initially observed to possess an unusually slow rotation period of 20 days, leading astronomers to hypothesize the presence of an unseen companion moon responsible for this sluggish rotation ...

Planetary scientists continue to debate what Sedna’s presence says about the history of our solar system. Now, S. Alan Stern of the Southwest Research Institute in Boulder, Colorado, says large bodies ...

In the frozen outskirts of the solar system, a reddish dwarf planet orbits in silence. Known as Sedna, it is so distant that one trip around the Sun takes more than 11,000 years. For much of that time ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. What’s three times further out than the planet Neptune, ...