Mars is at its closest and brightest this week. And it’s in view all night – almost. Tonight, it’ll vanish for a while for skywatchers from western Africa to the American west coast – hidden behind the Moon.

The disappearing act is an occultation. The word comes from Latin, and means “to hide” or “to cover up.” And the occultation is the result of the geometry of the solar system.

Mars and the other planets all stay close to the Sun’s path across the sky, the ecliptic. So does the Moon. But their orbits are tilted a little bit with respect to the ecliptic. So most months, the Moon and Mars pass close to each other, but they don’t overlap. The arrangement has to be just right for the Moon to occult the Red Planet.

Occultations come in clumps, when Mars and the Moon are in phase with each other and with the ecliptic. They’re in one of those phases now. There was an occultation last month, and there’s another one next month.

Tonight’s occultation takes place during the evening hours. The Moon will drop toward Mars, which looks like a bright star, then pass in front of it. The entire occultation will last about four hours. But from any given location, Mars will be out of sight for no more than about one hour. The occultation will be visible across the contiguous United States, eastern Canada, and most of Mexico. Mars and the Moon will stay close together for the rest of the night.

More about Mars tomorrow.

Script by Damond Benningfield