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Moon sweeps through Taurus the Bull

These next few mornings – August 6 and 7, 2018 – in the predawn hours, the waning crescent moon will be shining in front of the constellation Taurus the Bull. Look for the moon in the vicinity of Aldebaran, Taurus’ brightest star, and also the Pleiades star cluster.

To know precisely when Aldebaran and the moon rise into your sky, check out this U.S. Naval Observatory page.

Here’s a gorgeous view of the predawn sky, taken from Australia in late July, 2017 by our friend Yuri Beletsky. The bright object is the planet Venus. Aldebaran is the reddish star above Venus (part of the V-shaped Hyades cluster). The little dipper of the Pleiades cluster is to the left of Aldebaran. The large, prominent constellation Orion is on the right.

The lit side of a 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 6, 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 6, and then 24 hours later, before dawn on August 7. You’ll see that the moon has moved eastward in front of Taurus.

In fact, as seen from some north-central Asia, the moon will actually occult (cover over) Aldebaran in the predawn sky on August 7. Click here for more about the occultation of Aldebaran.

Occultation of the star Aldebaran by the moon. In this photo – taken March 4, 2017 – Aldebaran has just emerged from behind the moon. Photo by Gowrishankar Lakshminarayanan.

Bottom line: Before dawn on August 6 and 7, look for the moon in the vicinity of the constellation Taurus’ two most prominent signposts: the star Aldebaran and the Pleiades star cluster.

Bruce McClure