2021, January 20: Mercury, Bright Moon, Mars Conjunction

Mercury, January 20, 2021
2021, January 20: Mercury is low in the west-southwest during bright evening twilight.

January 20, 2021:  Mercury is low in the west-southwest after sunset.  The bright moon is to the lower right of Mars, while the Red Planet passes planet Uranus.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:13 a.m. CST; Sunset, 4:51 p.m. CST.  (Note that sunset is approaching 5 p.m. CST) Check local sources for sunrise and sunset times for your location.

During bright evening twilight, Mercury is over 7° in altitude above the west-southwest horizon.  A binocular is needed to see the speedy planet hiding in the bright twilight.

Moon near Mars-Uranus conjunction, January 20, 2021. Planets align. Mars passes Uranus this evening.
2021, January 20: The bright moon is 7.3° to the lower right of Mars. The Red Planet passes 1.6° above the planet Uranus.

The moon is near Mars this evening.  One hour after sunset, the slightly gibbous moon is 7.3° to the lower right of Mars.  The moon was at its First Quarter phase at 3:02 p.m. CST.

The Red Planet is dimming as our planet moves away after passing between Mars and the sun during October 2020.  The increasing distance means the planet appears smaller through a telescope and dimmer to the unaided eye.

Mars passes 1.6° above dim planet Uranus this evening. To find it, first locate dim 19 Arietis (19 Ari on the chart).  The star is 0.7° to the lower left of Mars.  Use a binocular to locate the aquamarine “star” that is slightly larger than twice the Mars – 19 Ari distance below Mars.  You’ll need at least 100x in a telescope’s eyepiece to see the spherical nature of the planet.  The planet does not appear large even with that telescopic magnification, just appearing as an ultra-miniature world at its distance from Earth.

Read about Mars during January.

Detailed Note: One hour before sunrise, Regulus (α Leo, m = 1.3) is less than 30° up in the west. If you’re still looking for Venus, it is over 3° in altitude in the southeast at 30 minutes before sunrise.  The moon is at its First Quarter phase at 3:02 p.m. CST. Jupiter sets at Civil Twilight. At this time, Mercury is over 7° in altitude in the west-southwestern sky. Nearly 63° in altitude in the south, the moon (7.8d, 51%) is 7.3° to the lower right of Mars.  The Red Planet passes 1.6° above Uranus.  The planet is 8.8° below Hamal and 0.7° to the lower left of 19 Ari.

Read more about the planets during January.

For a consolidated view of the daily activity of the planets and moon, subscribe to the Sky Calendar from Abrams Planetarium for $12 for a year. Each month’s sky events are displayed in calendar form. The opposite side of the page includes a star map. This is an easy reference to put on your refrigerator or bulletin board. No technology needed! Monthly calendars are mailed each quarter.


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Categories: Astronomy, Sky Watching

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