Don’t peek at the answer until you’ve given this a good try! Then, scroll down a bit and the truth will be revealed to you.
What in the world is it?
Now, I know you’re thinking that this is some kind of swirly phenomenon related to a crater on the Moon or some other solar-system body. And you’d be partly right. You see, this image, taken by the European Space Agency’s SMART-1 spacecraft in 2006, shows a bright feature on the surface of the Moon called the Reiner Gamma Formation. Now what’s curious about this feature is that the oval-shaped “crater” at left is not a crater! In fact early observations made from the ground originally misidentified it as a crater. Only later did detailed observations from orbit show that the region is totally flat!
What we see is a bright pattern of elliptical shape with small swirling extensions. The bright material stands out against the background, which is an old, dark lava plain in the Oceanus Procellarum on the near (visible) side of the Moon. The swirly feature measures some 30 by 60 kilometers. The origin of the Reiner Gamma Formation and other swirls occurring on the lunar surface is still unclear. So, the Reiner Gamma Formation could be an interesting site for future human exploration!