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2021, April 22: Brilliant Venus, Gibbous Moon, Mars

The Pleiades star cluster.

The Pleiades star cluster. (U.S. Naval Observatory)

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April 22, 2021:  Brilliant Evening Star Venus is making its first appearance in the western sky after sunset.  Look just above the horizon at 20 minutes after sunset.  The bright, gibbous moon is in Leo.  Mars approaches the star cluster Messier 35 in a darker sky.

Chart Caption – 2021, April 22: The bright, gibbous moon is 8.5° to the lower left of Regulus in Leo.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:59 a.m. CDT; Sunset, 7:40 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Venus is slowly making its way into the evening sky.  Twenty minutes after sunset, it is only 2° above the west-northwest horizon.  Use a binocular to first locate it.  Then try to view it without optical assistance.

Read more about Venus in our summary document.

One hour after sunset, the bright gibbous moon, nearly 80% illuminated, is about two-thirds of the way up in the south-southeast.  The lunar orb is 8.5° to the lower left of Regulus, “the prince,” the brightest star in Leo.

The westward facing Lion is one of the easier constellations to locate with a backwards question mark outlining the lion’s head. The shape is also known as the “Sickle of Leo,” after the tool used to harvest crops.  The haunches are made by a triangle with Denebola at the tail.

Chart Caption – 2021, April 22: One hour after sunset, Mars is about halfway up in the west near the feet of the Gemini Twin, Castor.

Farther westward, Mars is less than 40° up above the west horizon.  The planet is nearing the Gemini-Taurus border.  This evening, the planet is in Taurus and in two evenings it moves into Gemini.

The Red Planet is 4.6° to the lower right of Propus, “the projecting foot.”  The star is marked by Eta Geminorum, η Gem, on the chart.

Gemini resembles a stick figure pattern of Pollux and Castor with their arms around each other’s shoulders.

Chart Caption – 2021, April 22: Through a binocular, Mars and Propus (η Gem) are near the star cluster Messier 35 (M 35).

Use a binocular to spot the star and Mars near the star cluster Messier 35 (M35). The concentration has over 100 stars in it.  For those in darker areas without street lights, the cluster is barely visible to the unaided eye, although a challenge this evening with the bright moonlight.  A binocular reveals the bright stars.

With the bright moon in the sky, the binocular is necessary to see the dim stars.  As Mars approaches the cluster and the moon continues to brighten, the dimmer stars are more difficult to locate.

The cluster is not as bright or easily seen as the Pleiades cluster, because M35 is nearly 10 times farther away than the famous Seven Sisters cluster.

Such clusters are sometimes called open clusters or galactic clusters because they typically lie in the plane of the galaxy.  By locating and mapping them, along with other features, the shape of the galaxy was determined, along with the sun’s relative place in the Milky Way.

Here’s more about Mars during 2021.

Read about Mars during April.

Detailed Note: One hour before sunrise, Jupiter is 14.0° above the east-southeast horizon.  Use a binocular to find the nearby background stars.  Jupiter is 3.7° to the upper left of Deneb Algiedi, 0.9° to the lower left of μ Cap, and 2.3° to the upper right of ι Aqr. The gap between Jupiter and Saturn continues to widen as Jupiter moves faster eastward than the Ringed Wonder.  This morning Saturn – over 18° up in the southeast – is 14.3° to the upper right of Jupiter. Saturn is 1.3° to the upper right of θ Cap. Twenty minutes after sunset, Venus is over 2° up in the west-northwest.  Have you spotted it?  As the sky darkens further, the moon (11.0d, 78%) is about two-thirds of the way up in the sky above the south-southeast horizon.  It is 8.5° to the lower left of Regulus.  Use a binocular to spot the star Rho Leonis (ρ Leo, m = 3.8), 4.7° to the lower right of the moon.  Mars is farther westward, less than 40° above the west horizon, and 4.6° to the lower right of Propus. Use a binocular to spot the Red Planet, 2.5° to the lower right of the star cluster M35.

Read more about the planets during April 2021.

2021, December 29: Moon Nears Scorpion, Venus Departs

December 29, 2021: The morning crescent moon approaches Scorpius and Mars.  In the evening sky, four evening planets – Venus, Mercury, Saturn, and Jupiter – are lined up in the southwest.  Venus is rapidly leaving the evening sky.

2021, December 28:  Venus Slips, Mercury Hops

December 28, 2021:  Brilliant Venus is quickly slipping from the evening sky.  Mercury appears beneath Venus after sunset.  This duo is joined by Jupiter and Saturn.  In the morning, Mars is near Antares and the moon near Spica.

2021, December 27:  Mars – Antares Conjunction

December 27, 2021:  The Red Planet Mars passes Antares this morning before sunrise.  At the same hour, the moon is near Spica.  The three bright planets – Venus, Saturn, and Jupiter – are in the evening sky.

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