Is Sedna a Kuiper belt object?
NO. Sedna never enters the region of the Kuiper belt. The Kuiper belt is an icy asteroid belt just beyond Neptune. Extremely strong evidence shows that it has a rather sharp edge at 50 AU. Sedna never comes close than 76 AU. Calling Sedna an inner Oort cloud object makes much more sense. There are some KBOs that go very far from the sun like Sedna does, but they all have closest approach at about 35-45 AU. Sedna is special because it doesn’t come any closer than 75 AU to the sun. We believe that this is because of the effects of passing stars, as described above. A second speculative explanation for Sedna’s orbit is that a larger body, perhaps Mars-sized or larger could exist at around 70 AU in a circular orbit and could have caused Sedna to get thrown into its strange orbit. If such a planet existed, we would likely have already found it in our survey, though there are still a few places left to hide. How was Sedna found? We have been conducting an ongoing survey of the outer solar sy
