Earth mesmerizes in a new video from space, taken by cameras onboard China's Tiangong station in orbit. Our home planet displays its characteristic blue color as China's completed Tiangong space station, adrift high above the planet, appears in the foreground. The viewer glides over Earth at a gentle pace. At moments, the station is hidden from view, and Earth appears to roll underneath, like a marbled bowling ball. Sometimes cameras pick up the shadows that clouds cast onto the watery world below, and occasionally the sun shines a soft spotlight. The station is complete, and now continuously crewed. As of…