Sky ArchiveTonight

Moon near star Aldebaran on February 3

On February 3, 2020, you’ll find the waxing moon near Aldebaran, the brightest star in the constellation Taurus the Bull. Ruddy Aldebaran depicts the Bull’s fiery red eye at the tip of a V-shaped pattern of stars representing the Bull’s face.

You’ll see Aldebaran because it’s bright, but will you see the rest of the V-shaped face of the Bull? Because of the lunar glare, you might not. If you do make out the V pattern, know that – unlike many star pattern on our sky’s dome – these stars are associated in space. The V of the Bull is an actual star cluster, called the Hyades. Aldebaran isn’t part of this star cluster. The bright red star appearing at one tip of the V is a chance alignment, with the Hyades cluster at more than twice Aldebaran’s distance away. Starting around around February 12, when the moon drops out of the early evening sky, it should be easy to view the Hyades in a dark sky.

After the moon and Aldebaran first pop into view, at nightfall, they’ll continue to move westward as Earth spins under the sky. These two luminaries will set in the west in the wee hours after midnight.

Want to know when the moon sets in your part of the world? Visit Sunrise Sunset Calendars and remember to check the moonrise and moonset box.

Despite the lunar glare, you might also see the Pleiades star cluster, otherwise known as the Seven Sisters, to the north of the moon and Aldebaran. Each month, for many years to come, the moon will pass to the north of Aldebaran but to the south of the Pleiades star cluster. But each month, the moon will travel farther north in front of Taurus, until it goes so far north that it stages of series of 79 lunar occultations of Alcyone (Pleiades’ brightest star) from September 5, 2023, until July 7, 2029.

Star chart of constellation Taurus with ecliptic line running through it.
When the moon is no longer around to guide you, use Orion’s Belt to find Aldebaran. Orion’s Belt, at the lower left, always points in the direction of the constellation Taurus the Bull. The star Aldebaran resides to the south of the ecliptic and the Pleiades star cluster to the north of the ecliptic.

The moon and Aldebaran go westward across the sky tonight for the same reason that the sun goes westward during the day. The Earth rotates from west to east on its rotational axis. So, each day, as the Earth spins full circle beneath the heavens, the sun, moon, stars and planets all appear to go across the sky from east to west daily.

At the same time, tonight’s moon on February 3, 2020, is actually traveling eastward in front of the constellation Taurus the Bull at the rate of about 1/2 degree (the moon’s angular diameter) per hour. Relative to the backdrop stars of the zodiac, the moon travels on the average of about 13 degrees per day.

If you watch the moon at the same time over the next several nights, you’ll see the waxing gibbous moon farther east relative to the backdrop stars than on the previous night, as shown on the sky chart below. As it moves, the moon is edging toward being opposite the sun on our sky’s dome; in other words, it’s edging toward full moon, which will come on the night of February 8-9.

Read more: Will February’s full moon be a supermoon?

Chart of moon inside Winter Circle of stars.
In the coming evenings, look for a bigger star pattern. Aldebaran will be part of this bigger pattern, too. On February 4 and 5, 2020, the moon will be passing in front of this large circular pattern of bright and colorful stars. It’s called the Winter Circle. Read more.

Bottom line: This evening – February 3, 2020 – use the moon to find Aldebaran, the brightest star in the constellation Taurus the Bull.

February 3, 2020
Sky Archive

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Bruce McClure

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