2021, March 7: Morning Moon, Centaur, Planet Trio

2021, March 7: Sagittarius the Archer walks across the southern horizon during the early morning hours of March. The group resembles a teapot.
2021, March 7: Sagittarius the Archer walks across the southern horizon during the early morning hours of March. The group resembles a teapot.

March 7, 2021: This morning before sunrise, the crescent moon is near Kaus Borealis in Sagittarius.  Three planets, Jupiter, Mercury, and Saturn, are visible before sunrise in the east-southeast.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:15 a.m. CST; Sunset, 5:48 p.m. CST.  Check local sources for sunrise and sunset times for your location.

Morning Sky

This morning the crescent moon is less than one third of the way up in the south-southeast during early twilight.  It is above the stars of the “Teapot of Sagittarius”.

In mythology, Sagittarius was a centaur with the upper body of a man and the lower body and legs of a horse. In mythology, unlike other brutal centaurs, this one was helpful, and taught medicine and hunting.  Sometimes the constellation has the moniker “the Archer.”

Artwork shows a westward facing creature with an arrow ready to fly from its fully extended bow.

The names of the stars confirm the artistic portrayals of the bow:  Alnasl (“the point of the arrow”), Kaus Borealis (“the northern part of the bow”), Kaus Media (“the middle part of the bow”), and Kaus Australis (“the southern part of the bow”).

Other stars name the archer: Rukbat (“the archer’s knee”) and Arkab (“the archer’s Achilles tendon).

Today, many know the shape of Sagittarius as a “teapot.”  This is known as an asterism.  Such patterns are not official shapes but they are groups of stars within constellations.  The most famous asterism is the Big Dipper.  The seven stars are part of the greater pattern known as the Big Bear (Ursa Major). Others include Little Dipper, Great Square of Pegasus, V of Taurus, Winter Triangle, and Summer Triangle, although the latter pair of triangles connect bright stars in three constellations.

This morning the moon is 1.2° to the right of Kaus Borealis. 

2021, March 7: A binocular view of the crescent moon, Kaus Borealis, and Messier 22, a globular star cluster.

Use a binocular to see the moon, the star, and an interesting star cluster to the left of the star.  Unlike the Pleiades star cluster that has dark sky between the stars, this morning’s cluster has a cotton ball appearance with the stars appearing to be packed together.  It is known as a “globular cluster.”  Clusters like the Pleiades (known as an open cluster) and the globular clusters tell us about the shape and structure of the galaxy as well as our location in the Milky Way.

2021, March 7: Jupiter, Mercury, and Saturn are visible in the east-southeast before sunrise. Use a binocular to see them during bright twilight.

Three planets are emerging from the sun’s bright glare.  To see them you’ll need a clear horizon toward the east-southeast.  Saturn is visible about 45 minutes before sunrise.  Jupiter, the brightest, and Mercury are above the horizon by 30 minutes before sunrise.  By that hour you’ll need a binocular to see them during bright twilight.

At that hour, Jupiter is over 5° in altitude.  Mercury is 1.8° to the Jovian Giant’s lower left.  Both are within the same binocular field.  Saturn, outside the field, is 8.9° to the upper right of Jupiter.  Find Jupiter then move the binocular slightly to the upper right to see dimmer Saturn.

Detailed Note: One hour before sunrise, the moon (23.6d, 34%) is nearly 17° up in the south-southeast. It is 1.2° to the right of Kaus Borealis (λ Sgr, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius. Use a binocular to see the moon with the star as well as the globular star cluster M22 (NGC 6656), 2.4° to the upper left of the star.  Move the lunar crescent and the star to the lower left section of the binocular field.  While not an ideal hour to view them, the gaseous nebulae – Lagoon Nebula (M8, NGC 6523) and Trifid Nebula (M20, NGC 6514) – become visible to the upper right of the moon and the star.  At least the dim stars that help define the clouds’ locations are visible. As the sky brightens further, Saturn is visible low in the east-southeast, about 7° above the horizon.  Jupiter is 8.9° to the lower left of Saturn.  By 30 minutes before sunrise, use a binocular to see Jupiter and Mercury (m = 0.0), 1.8° to the Giant Planet’s lower left. One hour after sunset, Mars is high in the west-southwest among the starfield of Taurus.  It is approaching an imaginary line from Alcyone to Aldebaran (α Tau, m = 0.8).  This evening Mars is 3.2° to the upper left of Alcyone and 1.5° to the lower right 37 Tau.

Read more about the planets during March 2021.


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