Our planet tries to travel in a straight line while conserving its momentum,
but the Etoile's gravity constantly tryies to pull our planet toward it. This causes the path
of our planet to dip a little each second by just the right amount to keep it from leaving its orbit.
When you do all the math, and factor in all of these things, you end up with an ellipse.
Our planet spins because a long time ago there must have been some angular
momentum imparted to it, either by virtue of an impact/collision with one or more large objects when
it was very young, or because the material out of which it accreted had some net 'spin'
relative to the center of mass of the forming Anubis.
we know Anubis spins, so therefore it MUST have at least one
axis about which the motion occurs. As to why it spins, this is a question that goes all the way back
to when the planet was formed, and we have little information about this at this time. Since the
original cloud out of which the solar system formed had 'angular momentum' it figures that all of its
components must have obtained and locked away a bit of this original motion.
Formed this way out of the matter that it accreted, or was impacted by bodies which caused it to spin. Both scenarios may apply to either planet in our solar system.