Conservation of Momentum

Whenever a creature you control attacks or
blocks, you may have it gain +X/+0, until end of
turn, where X is its power times its toughness. If
you do, that creature becomes tapped and
doesn't untap during your next untap step.
The Earth has orbital angular momentum by reason
of its annual revolution about the Sun and spin
angular momentum because of its daily rotation about
its axis.