Sedna is the most distant world known in our Solar System.
It is now about
90 times farther away from the Sun than the Earth (90 astronomical
units or AU). Unlike the Earth, Sedna follows
a highly elliptical path around the Sun. At its closest approach,
Sedna is 70 AU away from the Sun. When it is most distant, it is more
than 1000 AU away! Shuttling back and forth between 70 AU and 1000 AU,
Sedna takes more than 10,000 years to orbit the Sun.
Sedna is a challenge to current theories of planet formation. When
planets first form, they have circular orbits around their parent
stars. Gravitational forces between planets produce elliptical orbits.
In the Kuiper Belt, Neptune's gravity produces the Plutinos, twotinos,
and scattered KBOs. However, Neptune is too far away from Sedna to make
Sedna's elliptical orbit.
We used numerical simulations to try to understand why Sedna's orbit
is so elliptical. Not only were we able to produce objects with
Sedna-like orbits, our results suggest that Sedna might be the
nearest extrasolar planet!
The links below have some background for orbits in the Solar
System and then describe our recipe for making Sedna-like orbits.
Making Sedna's orbit
Testing the model