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 ...

NPR's Madeleine Brand talks with NPR's Ira Flatow, host of Talk of the Nation Science Friday, about this week's announcement of the discovery of a new "planetoid" astronomers have dubbed Sedna. This ...

Astronomers announced Monday they had discovered the most distant object ever detected in the solar system -- a fiercely cold object neither planet nor comet, but a mysterious fossil remnant of a time ...

When the distant planetoid Sedna was discovered on the outer edges of our solar system, it posed a puzzle to scientists. Sedna appeared to be spinning very slowly compared to most solar system objects ...

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 ...