Earth's moon

The Moon is the natural satellite of the planet Earth, a big ball of rock orbiting Earth.

"Alpha/Omega"
After the Autobots discovered the whereabouts of the Decepticon space bridge, Megatron had it moved to the opposite side of the Moon from Earth.

"Moon Breaker"
The Autobots and Optimus Prime travel to the moon to prevent the Stunticons from recovering a dangerous device. They are successful in destroying the plasma thermal accelerator module and they captured the Stunticons as well.