Almost-Full Moon Rolls Over Aldebaran Tonight

This binocular view map shows the moon on its approach to Aldebaran at 9 p.m. local time tonight (Dec. 12) from Duluth, Minn. 48 minutes later, the moon’s left edge will cover the star in an event called an occultation. Map: Bob King, Source: Stellarium

As a warm-up to tomorrow night’s meteor shower, how about an occultation appetizer? Tonight, the one-day-before-full moon will cover Aldebaran, the brightest star in Taurus the Bull. Skywatchers across the U.S., Canada and even Europe can watch the moon slowly move across the Hyades star cluster before it occults the bright star. For many, this all happens during convenient evening viewing hours.

Tale of two cities. These simulations show where Aldebaran will meet the moon as viewed from Duluth and New Orleans tonight. Disappearance occurs at 9:48 p.m. local time for Duluth and 9:41 p.m. for New Orleans. The shift in position against the background stars is caused by parallax, or seeing the moon from two widely space locations. Maps: Bob King, Source: Stellarium

Aldebaran happens to lie near the path taken by the moon as it ambles around the sky each month, moving from one zodiac constellation to the next. For the past few and many more months ahead, the moon will regularly occult the bright star, affording many opportunities to witness these interesting events.

Make no mistake. The moon will be bright tonight, so throw a pair of binoculars around your neck. Then you’ll easily see the moon slowly encroach on Aldebaran until the moon’s shaded limb (edge) moves over the star, causing to blink out in a split second. A small telescope is even better because you don’t have to hold it steady. But both will work.

The occulation is visible anywhere between the two curved white lines. You can see it covers the U.S., part of Central America and Canada. Click for a list of times for various cities. Times shown will be UT or Universal Time. To change to Eastern Standard, subtract 5 hours; Central, 6 hours; Mountain 7 hours and Pacific 8 hours. Credit: Occult 4.2 software

The speed with which Aldebaran disappears from view is amazing and will give you a true sense of how fast the moon moves — about 2,300 mph (3,700 km/hour)! If you’re patient, you can watch the star return on the opposite or western side of the moon about an hour later. Disappearance and reappearance times vary depending on where you live, so click here for a list of over 1,100 cities to find the exact times for your location.

Clear skies!