This isn't a boomerang in the traditional Aussie mode, and it's not being thrown by a guy in a big hat. More awesomely, this is a boomerang being thrown on the International Space Station.
In space, no one can hear you cheer for a guy throwing a boomerang. Which is a shame, because this astronaut on the ISS does it with such aplomb. He spins one of those light, three-branched boomerangs out, and has it come back to him - managing to keep himself still by wedging himself in a doorway.
We already know about the physics of boomerangs. At any point in time one arm spins forward into the throw and one arm spins backward. The forward-moving arm rushes through the air faster than the backward-rushing arm. The air exerts a pressure on the boomerang and so the boomerang gets torqued and turns. This process wasn't theorized to have anything to do with gravity, but here we have proof. Gravity isn't needed to get a boomerang to come back to you. All that's needed is a steady hand, some air, and a space station.
I especially love that moment when he fumbles a catch slightly and the boomerang just hangs there. Awesome.