China’s new space plane returned to Earth on Sept. 6th. But it left something behind in orbit, an item of unknown character called “Object A” by the US military. Last night in the Netherlands, Marco Langbroek tracked it across the sky using a hand-pointed video camera. “It showed slow but marked brightness changes, between magnitude +4 and invisible (fainter than +7),” says Langbroek. “The light curve shows two brightness peaks, and two major fading episodes. Peak-to-peak period is about 80 seconds, so if this is due to a tumble, it is a slow tumble.“ Object A is also a source...