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No-Brainer Celestial Spectacle

Moon Occults Aldebaran on January 19

Put this in the category of a beautiful sunset or a full moon rising over a lake--an elegant natural phenomenon that just about everyone can appreciate.

A large gibbous moon will occult--or block out--the bright star Aldebaran on Tuesday, January 19, shortly after 9:00 p.m. EST. All you have to do is look due south at the moon, with the red giant star Aldebaran astride it, until the moon (moving left against the background stars) passes in front of the star. Poof, it's gone!

Because the star is a point of light, it will disappear in an instant (around 9:05 p.m. EST as seen from South Bend, IN) when the partially darkened edge of the moon moves in front of it. Around 10:22 p.m. the star re-emerges along the illuminated edge of the moon. For times at other locations, see IOTA predictions for Alpha Tau. With your naked eye you can witness the star disappear, but a magnified view, whether with binoculars or a telescope, amplifies the experience.

Since you're out stargazing, notice dominant Orion with the hunter's three belt stars pointing up and right toward Aldebaran, then go beyond to the Pleiades star cluster. If the cluster looks like a carmaker's logo, it's because a Japanese name for the Pleiades is Subaru. If you follow Orion's three belt stars down and to the left, you see the brightest star in the night sky--the star Sirius in the constellation of Canis Major, the Great Dog.

Sometimes the most profound moments in stargazing come in the quiet when you can discern the motions of the solar system with your naked eye. Enjoy the simplicity of the moon occulting a brilliant star as you realize everything in space is in motion. Another upcoming event is the 2016 transit of Mercury on May 9, when you can see the inner planet pass directly in front of the sun.

Added Jan. 19:

  • Correction regarding this star appearing as a point of light... J. Kelly Beatty, Sky & Telescope Senior Editor writes: "Aldebaran has a large apparent disk as stars go, 21 milliarcseconds wide. That's as big as a pea seen from just 15 miles (25 km) away. So you might see Aldebaran fading and reappearing not quite instantaneously if the Moon's edge skims it at a low angle from your location." - See more at:

  • Saw the moon and Aldebaran last night, even though it was supposed to be cloudy weather. So don't give up because of a weather forecast. Both of these objects are bright. You have to go outside and look. Or join us at Fiddler's Hearth Public House in South Bend, IN, to view the moon with telescopes.


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