MOVA's auto-rotating globes are mesmerizing little desk accessories that turn themselves by using ambient light and hidden magnets. It's an endlessly intriguing trick, and rather soothing to watch:

You don't need batteries or any desk-cluttering cord to power these globes. As long as the Earth's own magnetic field remains operational — and you've got MUCH bigger problems if that changes ? — then they'll keep on spinning, even in your hand. That last part is thanks to the transparent acrylic outer shell, which remains stationary while the floating-in-fluid inner globe does the actual spinning.

You don't need much light to power one either; fluorescent lighting, LED lights, or indirect sunlight from a window will get the job done just fine. In fact, they recommend not keeping it in direct sunlight, as well as avoiding the heat of high-powered halogen lights.

They've got a bunch of globes to choose from, including a variety of Earth styles/colorways (of course) alongside celestial bodies like Jupiter, the Moon, Mercury, Mars, and even a map of constellations. Most are 4.5" models that go for $160, although they do have 6" ones and 8.5" ones at higher prices.