2021, March 4: Mars – Pleiades Conjunction

2021, March 4: After sunset, Mars is 2.6° to the lower left of Alcyone, the brightest star in the Pleiades star cluster in this binocular view of the scene.
2021, March 4: After sunset, Mars is 2.6° to the lower left of Alcyone, the brightest star in the Pleiades star cluster in this binocular view of the scene.

March 4, 2021:  Evening planet Mars passes the Pleiades star cluster and its brightest star Alcyone.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:20a.m. CST; Sunset, 5:45 p.m. CST.  Check local sources for sunrise and sunset times for your location.

2021, March 4: Mars in Taurus with the Pleiades.
2021, March 4: Mars in Taurus with the Pleiades.

In the evening sky, Mars is the lone bright planet.  It is moving eastward in front of the stars of Taurus and close to the Pleiades.  While not as bright as it was at the beginning of the year, it is easy to spot with the bright winter stars.

Here’s where to find it:  Step outside about an hour after sunset. (The planet and surrounding stars do not set until over 6 hours after sunset, so there’s a wide window to see it.)  Look high in the west-southwest.  A small group of dim, tightly packed stars will catch your eye.  This is the Pleiades star cluster.  Mars is to the lower left of the cluster.

2021, March 4: Mars in Taurus with the Pleiades.
2021, March 4: Mars in Taurus with the Pleiades.

Tonight, Mars passes the brightest star in the cluster, Alcyone. (Do not confuse Mars with Aldebaran, the reddish star to the upper left of the Pleiades) The separation is 2.6°.  It’s not a close conjunction.  Anytime a bright planet treks through the field is an interesting view.

April 2 2020 Venus and Pleiades
2020, April 2: Venus nears the Pleiades (Photo by Tim S.)

Venus trekked through the region about a year ago.

The grouping is easily visible to the unaided eye. A binocular reveals many blue, and blue-white stars in the Pleiades star cluster.

Here’s more about Mars during 2021.

Read about Mars during March.

Detailed Note: One hour before sunrise, the moon (20.7d, 68%) is about 30° up in the south-southwest.  It is between Gamma Librae (γ Lib, m = 3.9) and Iota Librae (ι Lib, m = 4.5).  The lunar orb is 3.9° to the lower right of γ Lib and 3.5° to the upper left of ι Lib.  Three planets are in the east-southeast before sunrise.  Forty-five minutes before sunrise, Saturn is over 6° in altitude in the east-southeast.  Fifteen minutes later, Jupiter is nearly 5° in altitude, over 8° to the lower left of Saturn. Use a binocular to find it with Mercury 0.6° to Jupiter’s upper right.  One hour after sunset, Mars is less than 60° up in the west-southwest, 2.6° to the lower left of Alcyone, as the Red Planet passes the star this evening.

Read more about the planets during March 2021.

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