Sedna is at present over 90 AUs away ( An AU is an Astronomical Unit, The Distance of the Earth from the Sun, 93 million miles ). Sedna is about 1,800 km in diameter, slightly smaller than Pluto and nearly 3 times as far away. Its orbit is highly elliptical, passing closest to the Sun at 75 AU. It orbits once every 12,000 years.

Its elliptical orbit means that it is only detectable to us for a period of 60 years out of 12,000. This means that there is only a 1 in 60 chance of seeing it, and that there are possibly 60 or more Kuiper Belt objects of at least Sedna's proportions. Only a half dozen or so of the newly discovered objects are near Pluto's or Xena's proportions.