According to Inuit legend, the goddess Sedna lives beneath the frigid Arctic seas. And so in late 2003, when Caltech’s Michael E. Brown, working with Chadwick Trujillo of the Gemini Observatory and David Rabinowitz of Yale University, discovered an outer Solar System object whose surface temperature never rises much above 30 K, they proposed that it be named after the Inuit deity. 1
The minor planet Sedna, whose official designation is 2003 VB12, has a number of interesting properties. It is red like Mars, roughly 1500 km in diameter, and has a rotational period much longer than is typical for minor planets. But it is Sedna’s record-breaking perihelion combined with its highly eccentric orbit that have planetary scientists most intrigued. If, as expected, other Sedna-like objects are soon found, the clues they leave promise to change scientists’ view of the Solar System.
Since the autumn of 2001, Brown...
