The event above looks a bit like what you might expect to see before a looming UFO touches down or beams you up, but the phenomenon shown is actually totally natural.

It’s called a fallstreak hole (also a “hole punch cloud” or “cloud hole,” among others) and it occurs when the water in the clouds dips below freezing temperature, but hasn’t frozen due to lack of “ice nucleation”—something for the water to freeze around to kickstart the formation of crystals. There’s even a term for water that’s below freezing but still in liquid form: supercooled.

When a cloud contains all that supercooled water and then something like an airplane triggers the formation of ice crystals, they quickly freeze up and drop or evaporate, leaving an empty space where the water molecules used to be.

Redditor big_mac_heart_attack (a.k.a. photographer David Barton) snapped the fallstreak hole over eastern Victoria, Australia earlier this month. The occurrence has only been fully understood in recent years, but it still confuses and excites observers on the ground below. And while it’s no supernatural occurrence, the science behind the fallstreak hole is still worth a marvel.

[via Colossal]