On Sept. 15th, Stephen O’Keefe of Houston, Texas, was driving to work just before sunrise when a dark ray sprung up from the eastern horizon. “It was very tall and all by itself,” says O’Keefe, who snapped this picture using his mobile phone:

The solitary nature of the dark ray makes it look less familiar than it actually is. This is an example of a crepuscular ray–essentially a shadow of a distant cloud carving an immense tube of darkness in the early morning sky. Drivers see these rays all the time. Usually they appear in fan-shaped groups that trace the ragged edges of clouds. This time, we’re guessing, a single dense cloud did the trick.

The sun isn’t the only thing that can make such a ray. The full Moon can do it too. Be alert tonight for crepuscular rays spreading from the eastern sky as the Harvest Moon rises into the night.

Source: Space Weather.com