The Sun illuminates about half of the lunar hemisphere that faces our way this evening. The angle of the sunlight makes it easy to see the patterns of light and dark on the surface.

One of the dark markings is the Sea of Serenity — an ancient volcanic basin that might have caused the Moon to “wander” a bit.

The Sea of Serenity formed billions of years ago. A giant asteroid slammed into the Moon, creating a crater that’s more than 400 miles wide. Over hundreds of millions of years, dense magma from deep below the surface oozed into the crater, forming a smooth, dark plain.

The volcanic rock was much heavier than the rocks around it. And a recent study suggests that caused the Moon to tilt over a bit. So its poles changed position — by about 300 miles.

In fact, the study says that several big events caused the lunar poles to wander. Each event created an area of dense rock at the surface, which shifted the Moon’s balance. So each event caused a shift in the poles.

The last of these events took place billions of years ago. So today, the Moon is stable — its poles haven’t moved in a long time. And that’s important for lunar exploration. Deep craters at the poles haven’t seen the Sun in billions of years. So vast deposits of ice are trapped there — possible resources for future explorers.

Look for the Moon in the southwestern quadrant of the sky this evening. The bright star Antares, the heart of the scorpion, lurks nearby.

Script by Damond Benningfield