2021, April 21: Evening Star Venus, Gibbous Moon, Mars

April 21, 2021: Evening Star is making its first appearance in the west-northwest shortly after sunset.  The gibbous moon is near Leo, while Mars is near the foot of Castor.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:01 a.m. CDT; Sunset, 7:39 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Venus is emerging from the bright glare of the sun, but continues to be a challenge to see.  It is very low in the west-northwest about 20 minutes after sunset.  Try to observe the planet with a binocular to locate it and then attempt to find it without optical help.

Read more about Venus in our summary document.

2021, April 21: The bright gibbous moon is near Leo.
Chart Caption – 2021, April 21: The bright gibbous moon is near Leo.

One hour after sunset, the bright moon is over two-thirds of the way up in the south.  The lunar orb is to the right of the Sickle of Leo.  In the starfield, it 7.5° to the right of Algieba, “the forehead” and 7.6° to the upper right of Regulus.

2021, April 21: One hour after sunset, Mars is less than halfway up in the west near the feet of Castor.
Chart Caption – 2021, April 21: One hour after sunset, Mars is less than halfway up in the west near the feet of Castor.

Mars is farther west, less than halfway up in the sky above the west horizon.  The Red Planet is in front of the stars of Gemini.  It is 5.1° to the lower right of Propus, “the projecting foot” (η Gem on the chart).

Mars is approaching the star cluster Messier 35 (M35), a distant star cluster like that of the Pleiades star cluster and Hyades star cluster.

2021, April 21: In this binocular view, Mars approaches the star cluster M35. Propus (η Gem) is in the field of view.
Chart Caption – 2021, April 21: In this binocular view, Mars approaches the star cluster M35. Propus (η Gem) is in the field of view.

Use a binocular to see Mars, Propus, and the star cluster together. Mars passes the star cluster in less than a week.

Here’s more about Mars during 2021.

Read about Mars during April.

Detailed Note: One hour before sunrise, Saturn is over 18° above the southeast horizon and 1.4° to the upper right of θ Cap.  Jupiter – 14.2° to the lower left of Saturn – is nearly 14° up in the east-southeast.  In the starfield, Jupiter is 3.6° to the upper left of Deneb Algiedi, 0.7° to the lower left of μ Cap, and 2.5° to the upper right of ι Aqr.  Use a binocular to note the changing position of Jupiter compared to the sidereal background.  Twenty minutes after sunset, Venus is over 2° above the west-northwest horizon.  In a darker sky forty minutes later, the moon (10.0d, 68%) is over two-thirds of the way up in the sky above the southern horizon.  It is 7.5° to the right of Algieba (“the forehead,” γ Leo, m = 2.0) and 7.6° to the upper right of Regulus.  In the west about 40° up in the sky, Mars is 3.1° to the lower right of the star cluster M35 and 5.1° to the lower right of Propus (“the projecting foot,” η Gem, m = 3.3). This trio of celestial treasures and other nearby background stars easily fit into the view of wide-field binocular.

Read more about the planets during April 2021.



Categories: Astronomy, Sky Watching

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