Moon, Aldebaran, Pleiades before bedtime

Late at night on September 7 and 8, 2020, watch as the waning gibbous moon sweeps in front of the constellation Taurus the Bull. You’ll be looking around midnight, or afterwards, or – if you’re not one to stay up late – get up before daybreak to view the moon and Taurus higher up in the sky on the mornings of September 8 or 9. The bright moon might make it tough to see the starlit figure of the Bull on these nights. But you should be able to make out Aldebaran, Taurus’ brightest star, as well as the tiny, misty, dipper-shaped Pleiades star cluster.

Then, when the moon moves away, look for the V-shaped Face of the Bull itself. The bright star Aldebaran marks one tip of the V.

Taurus is a far-northern constellation of the zodiac. That fact causes these stars to rise at an earlier hour in the Northern Hemisphere than in the Southern Hemisphere. The farther north you live, the earlier Taurus climbs above your northeast horizon. The farther south you live, the later Taurus comes up.

Want to see your specific sky view? Try Stellarium online

Or visit Sunrise Sunset Calendars, being sure to check the moonrise and moonset box, to find out when the moon rises into your sky.

Bright moon, large lunar halo, bright red star and star cluster.

View at EarthSky Community Photos. | Our friend Dr Ski in the Philippines caught the moon and Pleiades (the little cluster in the moon’s glare, at around 8 o’clock) on the morning of September 20, 2019, when they were in conjunction (same right ascension on the celestial sphere). You can also see Aldebaran here, the bright red star at about 5 o’clock. And a lunar halo! Dr Ski wrote: “I captured this image to check the field of view on my 40mm portrait lens. It’s 44° ?.” Thanks, Dr Ski!

When the moon travels in front of Taurus (or any constellation of the zodiac, for that matter), the moon can travel anywhere from 5 degrees north to 5 degrees south of the ecliptic.

A little over two years ago – on September 3, 2018 – the moon occulted (passed in front of) Aldebaran, presenting the final occultation of a monthly occultation series that started on January 29, 2015. But month by month, for the next few years, the moon’s trajectory will carry the moon farther north of Aldebaran yet closer to Alcyone, the Pleiades’ brightest star.

Then the monthly occultation series involving the moon and the Pleiades star Alcyone will begin on September 5, 2023, and conclude on July 7, 2029.

Sky diagram with arrow pointing from Orion to Aldebaran and the Pleiades.

When the moon moves away, try this. The 3 stars of Orion’s Belt always point to the star Aldebaran and the Pleiades star cluster. Image via Janne/Flickr.

For the Skidi Pawnee in the American Great Plains (Nebraska), the Pleiades cluster served as an important calendar marker. When they saw the Pleiades cluster through the smoke holes of their lodges just before dawn, they knew it was time to harvest the crops.

Star chart of constellation Taurus with Aldebaran and Pleiades marked prominently.

The ecliptic – the sun’s yearly path through the constellations of the Zodiac – passes through the constellation Taurus the Bull, to the north of the star Aldebaran and to the south of the Pleiades star cluster. The sun shines in front of Taurus from about May 14 to June 21, every year.

Bottom line: Are you a night owl? Before bedtime on September 7 and 8, 2020, look eastward for the moon, which shines in front of the constellation Taurus the Bull. If you’re an early bird, look for the moon and the constellation Taurus before daybreak on September 8 and 9, 2020.

Bruce McClure