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Moon sweeps through Taurus the Bull

In the predawn/dawn hours tomorrow – on August 15, 2017 – the moon will be at or near its last quarter phase, and in front of the constellation Taurus the Bull. Look for the moon in the vicinity of href=”http://earthsky.org/brightest-stars/aldebaran-is-taurus-bloodshot-eye”>Aldebaran, Taurus’ brightest star, and also the Pleiades star cluster. The moon, Aldebaran and the Pleiades go upward and westward throughout the wee morning hours.

If you’re a night owl, staying up past the midnight hour, you might see this celestial threesome – the moon, Aldebaran and the Pleiades – low in the eastern sky before your bedtime. To know precisely when Aldebaran and the moon rise into your sky, check out this U.S. Naval Observatory page.

From mid-northern latitudes, the moon, Aldebaran and the Pleiades shine high in the south to southeast sky in the dark hour before dawn.

Before dawn from the northern tropics, look high overhead for this threesome.

Before dawn from the Southern Hemisphere, look for the moon, Aldebaran and Pleiades in your northern sky.

The lit side of the waning moon always points in the direction that it travels in front the constellations of the zodiac. So as seen from around the world tomorrow morning, on August 15, the waning moon will be moving eastward toward the star Aldebaran at the rate of about one-half degree (one moon-diameter) per hour. That’s in spite of the fact that the moon always moves westward across the sky, due to the Earth’s rotation.

Contrast the position of the moon before dawn on August 15, and then 24 hours later, before dawn on August 16. You’ll see that the moon has moved eastward in front of the constellation Taurus. As seen from around the world, the moon will be much closer to the star Aldebaran on August 16 than August 15. See the sky chart below.

MULTIPLE MOON CHART

In fact, as seen from some parts of Earth, the moon will actually occult (swing in front of) Aldebaran on the night of August 15-16. We talk more about this occultation on our August 15 Tonight program.

Before dawn on August 15, look for the moon in the vicinity of the constellation Taurus’ two most prominent signposts: the star Aldebaran and the Pleiades star cluster.

BELOW TO AUGUST 15

The moon will pass in front of Aldebaran, as seen from some parts of Earth, in what astronomers call an occultation. Afterwards, Aldebaran will appear on the other side of the moon …

Moon on the morning of July 28, 2016, the morning of its occultation of the star Aldebaran (shown at left). Photo by Lunar 101-MoonBook.

Moon on the morning of July 28, 2016, shortly before it occulted the star Aldebaran (shown at left). Photo by Lunar 101-MoonBook.

This month’s occultation of Aldebaran is part of a long series of monthly occultations of this star by the moon. September 2016’s event will be seen from eastern parts of Africa, the Middle East and southwestern portions of Asia (India). The occultation will occur during the the nighttime hours on September 21-22. Aldebaran will disappear behind the lit side of the waning gibbous moon and then reappear from behind the moon’s dark side.

Occultation

Note the worldwide maps above. Everyplace inside the solid white lines is in a position to observe the lunar occultation of Aldebaran during the night of September 21-22. At the left side of this swath, the occultation happens at late evening, or around midnight. At or near the right side, the occultation occurs shortly before dawn. Click here to find out the occultation times for numerous localities in Universal Time.

How do I translate Universal Time to my time?

View larger. The moon actually occults - moves directly in front of -Aldebaran on the night of September 21-22. Click here for occultation times.

View larger. | The moon occults – moves directly in front of – Aldebaran on the night of September 21-22. Click here for occultation times.

For your convenience, we list a few occultation times in local time below:

Lunar occultation of Aldebaran on September 21-22, 2016.

Khartoum, Sudan (September 21-22)
Occultation starts: 11:39 p.m. local time on September 21
Occultation ends: 12:30 a.m. local time on September 22

Riyadh, Saudi Arabia (September 21-22)
Occultation starts: 11:57 p.m. local time on September 21
Occultation ends: 12:46 a.m. local time on September 22

Jaipur, India (September 22)
Occultation starts: 2:54 a.m. local time on September 22
Occultation ends: 4:17 a.m. local time on September 5

Click here for more on the lunar occultation of Aldebaran on the night of September 21-22. At this link, the occultation times are given in Universal Time. You must convert to your local clock time to know when Aldebaran disappears behind the lit side of the moon and then reappears on the moon’s dark side.

Bottom line: If you’re a night owl or early bird, watch the moon pass in front of the constellation Taurus the Bull over the next several days.

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Bruce McClure

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