Crescent Moon occults Aldebaran
Seconds before the waxing crescent Moon covered Aldebaran exactly 19 years earlier, on the night of April 10, 1997, Los Angeles astrophotographer Michael Stecker caught this shot using a 5-inch refractor. (The image in the homepage slideshow is a colored photo-illustration to suggest Sunday's blue-sky view.)

On Sunday afternoon, April 10th, you'll see the waxing crescent Moon hanging high in a sunny blue sky if the weather is as good as we hope it'll be. Look with a telescope from nearly anywhere in North America, and you can find something else too. Somewhere in the Moon's vicinity will be 1st-magnitude Aldebaran: a tiny yellow-orange spark shimmering in the blue. And if you're watching at the right moment, you can see Aldebaran snap out of view in the blink of an eye as the Moon's dark limb (invisible in the daylight!) covers it up.

The farther east you are, the later in the afternoon the occultation will happen, so the lower the Sun will be and the more readily you should be able to sweep up Aldebaran.

The event happens a little after sunset in much of the Canadian Maritimes. Along the East Coast from Maine to Miami, the Sun will still be about 3° to 12° above the western horizon. Farther west the Sun will be higher and the sky brighter, so the clarity of your air will matter more. Only northern Canada and Alaska miss the occultation completely.

Aldebaran will reappear from out from behind the Moon's bright limb up to an hour or more later, when the Sun will be lower and even, for the East Coast, may have recently set. But Aldebaran will be harder to see as it buds out from the sunlit moonscape, so you'd still need the telescope.

The Moon will be a thinnish, 17%-illuminated crescent. You’ll find it about 50° to the Sun's celestial east.

Some predicted times of the star's disappearance and reappearance, at cities from east to west:

Halifax: disappearance 8:00 p.m., reappearance 8:56 p.m. ADT.
Montreal,  d. 6:47,  r. 7:48 p.m. EDT.
Boston,  d. 6:51,  r. 7:56 p.m. EDT.
Toronto,  d. 6:39,  r. 7:46 p.m. EDT.
Washington, DC,  d. 6:43,  r. 7:55 p.m. EDT.
Atlanta,  d. 6:34,  r. 7:49 p.m. EDT.
Miami,  d. 6:57,  r. 7:50 p.m. EDT.
Chicago,  d. 5:25,  r. 6:39 p.m. CDT.
Kansas City,  d. 5:11 , r. 6:31 p.m. CDT.
Austin,  d. 5:07, r.  6:22 p.m. CDT.
Winnipeg,  d. 5:17,  r. 6:13 p.m. CDT.
Denver,  d. 3:51,  r. 5:11 p.m. MDT.
Edmonton,  d. 4:12, r.  4:36 p.m. MDT.
Vancouver,  d. 2:48,  r. 3:28 p.m. PDT.
Berkeley,  d. 2:21,  r. 3:37 p.m. PDT,
Los Angeles,  d. 2:21,  r. 3:42 p.m. PDT
Honolulu,  d. 10:29,  r. 11:28 a.m. HST.

Detailed timetables for 570 cities and towns, including in Mexico and the Caribbean, are on the massive website of the International Occultation Timing Association (IOTA). In the timetables are the altitudes of the Sun and Moon at the time of the event for each location.

That link brings up three tables: for Aldebaran's disappearance, reappearance, and the locations of the cities. The three are stacked without very obvious demarcations between them, so watch for the breaks as you scroll. The two capital letters designate the country; remember CA means Canada, not California.

Can you get good pix of this event? Post 'em in our Gallery!



Image of Deepspacehunter


April 10, 2016 at 5:56 pm

Thanks! Looking forward to it as I type..

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Image of Night Owl

Night Owl

April 10, 2016 at 8:10 pm

I was able to view Aldebaran as it reappeared at the moon's limb at 20:05 from my home in Virginia.Cloud cover interfered with the disappearance. I was using 20 x 80 binoculars to view the event.

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Image of David Fried

David Fried

April 11, 2016 at 11:42 am

I saw the occultation from my backyard in Boston itself, through a 6" Schmidt-Newtonian at 78x. I could not see the dark limb of the moon at all, so from my point of view Aldebaran was not so much occulted as . . . vanished in an instant. But I saw it again easily through 10 x 50 binoculars a few minutes after its reappearance

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