Looking Up: Pass-a-bull

Dec 12, 2016

trying to hit the bull's eye
Credit earthsky.org

This week on Looking Up Hal is right on target with this description of the moon occulting Aldebaran (the eye of the bull). 

About a year ago we talked about a very interesting and very bright star in the southern Colorado sky, Aldebaran. The brightest star in the constellation Taurus, Aldebaran is the 13th brightest star in the night sky. This bright red star is the bright red eye of Taurus the bull. And it’s visible nearly all night during the winter, unless of course, something gets in the way.

And something is going to get in the way tonight December 12, 2016. And that something is the brightest thing in the night sky, the moon. Yes, tonight the moon is going to pass in front of, or occult, Aldebaran, and you can watch it happen.

Occultations are not rare. In fact, if you think about it, as the moon circles the earth each month, it passes in front of, relative to viewers on earth, lots of stars and occasionally planets. But occultations of very bright objects are much rarer. Tonight a nearly full moon will blot out the star Aldebaran for over an hour.

So how do you watch it? Aldebaran is actually fairly easy to spot. In the constellation of Orion, the most dominant constellation in our sky right now, you need only find the three stars that make up Orion’s belt. Those three stars form a line going from the lower left to the upper right, so to speak to viewers in southern Colorado. If you follow the line of those stars to the upper right, you’ll find a bright red star Aldebaran.

At about 8:22 PM tonight the dark edge of the moon will slide over Aldebaran. Don’t look away, it will happen quickly. A little over an hour later, at about 9:33 PM, Aldebaran will reappear from the brightly lit other edge of the moon. It will be easier to see it disappear then reappear, because the Moon is so bright.

If you’d like to take a closer look at the occultation, or any of the other wonderful and amazing things in the sky, please visit CSASTRO.org for a link to information on our monthly meetings and our free public star parties! 

This is Hal Bidlack for the Colorado Springs Astronomical Society, telling you to keep looking up, Southern Colorado!