M. Zejmo

A bus schedule drifts: if you don't check it, you'll miss your ride. Planets around other stars have the same problem – their crossings of the star's disk gradually shift. The ExoClock project pooled 30,000 observations from Earth and space to refine the schedule for 620 distant worlds. For 45% of the planets, transits were found to be off by hours.

A spinning top launched into weightlessness doesn't just rotate around its axis: it also wobbles, like a drunken sailor. That's exactly how the asteroid Apophis behaves: it doesn't spin neatly but tumbles through space. On April 13, 2029, this celestial wanderer will whiz past at about 38,000 kilometers from Earth — closer than communications satellites.