From parts of the U.S., the Moon will briefly cover the heart of the lion tonight. The Moon will pass directly between Earth and the bright star Regulus, creating an occultation.

The Moon can occult Regulus because the star lies almost atop the ecliptic – the Sun’s path across the sky. The Moon stays close to the ecliptic, but it does move a little to either side. So occultations of Regulus come in groups. This one is part of a cycle that began last July and will continue through the end of this year. The occultations are separated by about 27 days, which is how long it takes the Moon to circle through the background of stars.

Each occultation is visible from a different part of Earth. In part, that’s because the Moon and Regulus are below the horizon as seen from much of the world. And the Moon is so close to us that there’s a big difference in the viewing angle across the globe. So from any specific location, sometimes the angle is just right, but more often it’s a little off.

This month, the angle is right for skywatchers in the eastern United States. For most of the rest of the country, the Moon will just miss the star. So all of us will see an amazingly close encounter between the Moon and the heart of the lion.

Only one more occultation in this sequence will be visible from anywhere in the contiguous United States – on April 25th. After that, we won’t see another one until 2044.

Script by Damond Benningfield