2021, January 10: Mercury, Jupiter, and Saturn, Group Closely

January 10, 2021:  Mercury makes a pretty triangle with Jupiter and Saturn, nearly 3 weeks after the giant planets’ great conjunction.  This close grouping is of three planets is unusual.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:17 a.m. CST; Sunset, 4:40 p.m. CST.  Check local sources for sunrise and sunset times for your location.

Speedy Mercury is with Jupiter and Saturn low in the west-southwest at about 30 minutes after sunset.  Because of the bright twilight, use a binocular to first locate bright Jupiter.  Saturn is 2.2° to the lower right of the Jovian Giant.  Mercury, brighter than Saturn and dimmer than Jupiter, is 1.6° to the lower left of Saturn and 2.8° below Jupiter.

This is the closest grouping since Mercury, Venus, and Mars clustered together on May 21, 2011.  The three planets fit within a circle that is 2°23’ in diameter.

Mercury joins Venus and Jupiter in 34 days (Feb 13) in a wider grouping (4°36’).  This grouping occurs when the planets are merely 10° from the sun.

From this date we wait until April 20, 2026 to see Mercury, Mars, and Saturn clustered in a 1° 40’ circle.

This evening the planets are setting early; this makes the window small to observe them before they disappear below the horizon.

Jupiter sets only 68 minutes after sunset.  To see this tight grouping star looking 30 minutes after sunset for about the next 15 minutes.

Detailed Note: Thirty minutes after sunset, Jupiter, about 7° up in the west-southwest, is 2.2° to the upper left of Saturn. Use a binocular to locate them, especially Saturn.  Mercury (m = −0.9) makes a pretty triangle with Jupiter and Saturn.  It is 1.6° to the lower left of Saturn and 2.8° below Jupiter. The three planets fit within a small circle (2°23’) This is the tightest grouping since Mercury, Venus, and Mars clustered together (2°8’) on May 21, 2011. Mercury joins Venus and Jupiter in 34 days (Feb 13) in a wider grouping (4°36’), although this grouping occurs a mere 10° west of the sun. From this date we wait until April 20, 2026 to see Mercury, Mars, and Saturn clustered in a 1° 40’ circle. Read about Mars during January.

Read more about the planets during January.