2021, March 4: Morning Moon, Planetary Triple

2021, March 4: During morning twilight, the bright moon is visible in Libra.
2021, March 4: During morning twilight, the bright moon is visible in Libra.

March 4, 2021: The bright moon is in Libra.  Jupiter, Mercury, and Saturn are in the east-southeast before sunrise.  Mercury nears a conjunction with Jupiter.

by Jeffrey L. Hunt

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

Morning Sky

This morning before sunrise, the bright, gibbous moon is about one-third of the way up in the south-southwest.  The lunar orb is in Libra between the dim stars Gamma Librae (γ Lib on the chart) and Iota Librae (ι Lib).

These stars were once part of the classic Scorpion.  The two stars that marked the claws, Zubeneschamali (“northern claw”) and Zubenelgenubi (“southern claw”) are the brightest stars in the Scales.

Libra is the only constellation in the zodiac (“circle of animals”) that is not a real or mythological living thing – Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Ophiuchus, Sagittarius, Capricornus, Aquarius, Cetus, and Pisces.  (Orion’s arm is part of the zodiac as well.  The planets and moon are sometimes visible in front of those stars.)

2021, March 4: Jupiter, Mercury, and Saturn are visible low in the east-southeast before sunrise.
2021, March 4: Jupiter, Mercury, and Saturn are visible low in the east-southeast before sunrise.

Three planets are visible before sunrise.  Saturn is first to appear and it is about 6° above the east-southeast horizon, about 45 minutes before sunrise.  Jupiter and Mercury are visible low in the east-southeast by 30 minutes before sunup, but a binocular is needed to see them during this bright phase of twilight.

Jupiter is the brightest planet of this trio. The Jovian Giant is only 5° above the horizon. This morning Mercury is 0.6°, slightly larger than the moon’s diameter in the sky, to the upper right of bright Jupiter.  Both easily fit into the same binocular field.  Saturn is over 8° to the upper right of Jupiter.  Put Jupiter to the lower left of the binocular field, then move the binocular slightly to the upper right to see Saturn.

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.



Categories: Astronomy, Sky Watching

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