March Sky Talk | Encore Performance Moon Hides Aldebaran!

In its monthly eastward orbit around the sky, our lovely satellite often passes in front of (or occults) objects beyond it, including planets, stars and even entire star clusters like the famed Pleiades.  Last December the Moon covered the bright star Aldebaran for the entire U.S.  Unfortunately, much of the country was overcast and the event clouded out.  On the late evening of March 4th the Moon will once again occult Aldebaran, giving skywatchers a second change to experience this game of “cosmic hide-and-seek.”

Fiery-orange Aldebaran lies in Taurus northwest of Orion, whose three prominent belt stars point directly at it—as a glance at your Scientifics Star and Planet Locator will show.  When evening falls on the 4th, a nearly half-full Moon will be positioned high in the southwestern sky.  An occultation of a bright star or planet can be a naked-eye event—especially when the Moon is in its crescent phase and most of the leading edge is still in darkness. This time its slow approach toward Aldebaran over a period of hours will be visible without optical aide.  But it will be bright enough that binoculars will likely be needed to see the actual disappearance itself.  One technique that may make it visible to the eye is to hold a piece of cardboard at arm’s length to block out the Moon’s illuminated surface.  But be careful to not cover the left edge of the Moon where Aldebaran will be disappearing!  It’s best to be sitting comfortably and use both hands to help keep your aim steady.

Aldebaran’s actual disappearance will be instantaneous, but assigning an exact time is a bit tricky since it depends on both an observer’s latitude and longitude.  As an example, for those living along the East Coast, the occultation is scheduled for:

  • 11:03 p.m. EST for viewers in Miami
  • 11:04 p.m. EST for viewers in Norfolk
  • 11:07 p.m. EST for viewers in Atlantic City
  • 11:11 p.m. EST for viewers in New York

Going inland changes these times by as much as half an hour or more, disappearance in Chicago being at 11:33 p.m. for example. (To find the times for your particular city, go to: http://www.lunar-occultations.com/iota/bstar/0305zc692.htm

Note that it’s given in Universal Time—that in Greenwich England—which is 5 hours ahead of EST.  The Miami event is listed as 04:03 UT on March 5th since it’s the next day there.) The best advice is to go outside at least 15 minutes before the scheduled times so you are sure to not miss the disappearance.  This will give you time to watch the Moon creep up on Aldebaran before covering it.  Even if you do miss the actual occultation at the instant it happens, you will have the thrill of seeing a star that was there just minutes before no longer in the sky!

One final thing to note: Aldebaran lies projected against the big V-shaped Hyades star cluster, a number of whose members will also be occulted that evening.  While it will be fun watching for these, binoculars will definitely be needed since they are all much fainter than Aldebaran itself.  Clear skies!

— James Mullaney

Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing.   His latest, Celebrating the Universe!, is available from HayHouse.com.