Funky Ball

This idea came to me...I have no idea why.

A transparent or translucent ball with illumination inside so there is a glow when seen rolling down the sidewalk.

The tough part.

Only one side glows!

The tougher part.

That side is always NORTH !  ( or South depending on your politics )

So here we have a ball rolling down a dark path with the same side always illuminated.  It should appear as if it is floating down the path because the illuminated side never changes position.

Options:

One color on NORTH and one on South. 

Perhaps color changing RGB LED's?

Perhaps a "head light" always illuminating direction of travel with a tail light.

The illuminated side is always the side in the direction the ball is rolling.


Methods:

Arduino and compass  or gyro/attitude shield?

Anyone ?