If Pluto is a planet, denying Sedna its planetary rights is gross injustice
In re to Sedna, perhaps it's originally a member of the OX/IX globular clusters that orbit further out, and send killer comets into the inner solar system every 26 million years, as they pass THROUGH each other(on nearly identical orbits). 65 million years ago(dino-whacking asteroid)is 2 1/2 cycles ago. At least Brian Marsden thinks it(OX/IX)is a plausible explanation...
Of course Pluto's status as a planet is still hotly debated. It could be a while before Sedna is properly renamed after a Roman or Greek diety.
Pluto is called a planet only because of tradition.
Oops! I just now detected the barb. Poor Sedna – low self esteem. It will probably become a rogue.