> Is the earth's orbit stationary with respect to the other planets?

Interesting physics problem...if all of the planets moved in step in the same plane, and say, the Earth, had a constant angular velocity, then wouldn't the other planets have to accelerate and deccelerate on their orbits to maintain position with the Earth?

Yes, the planets revolve around the sun, and due to the nature of their formation, pretty much in the same plane, but there are distinct differences in velocities and shapes of orbits, which is why you sometimes get planetary alignments (like just now, when several planets are visible in the night sky - Venus, Mars, Saturn, Jupiter and Mercury(?), I think it was) and more oftentimes, not.

For more detail, an astronomy textbook might be handy.

Bo"my head is spinning just thinking about the Karplus equation"urne