December 20, 2020: On Great Conjunction Eve, Jupiter is 0.1° below Saturn. As Jupiter passes Saturn, they are near each other for 3 nights. Great Conjunction Countdown: 1 day! Mars is farther east in Pisces with the moon between the three planets.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:15 a.m. CST; Sunset, 4:23 p.m. CST. Check local sources for sunrise and sunset times for your location.
One evening before the Great Conjunction occurs, the planets are low in the southwest as night falls. Jupiter is 0.1° below Saturn. When measured in minute fractions of a degree, Jupiter is 471 arcseconds from Saturn. Tonight, Conjunction evening, and December 22, the planets are very close. To the untrained eye, they might seem to be the same separation each evening, although Jupiter in its slow-pass meeting with Saturn is in a different orientation each evening.
Depending on your eyesight, you may need a binocular to separate Jupiter from Saturn. The planets do not merge into a single point.
Their separation is about the same size we see when we look at the Imbrium Basin, a large impact structure, on the moon. This dark circular region makes up part of the “Man in the Moon” feature and its easily visible when the moon is nearly full and during its waning phases.
The thick crescent moon is in the south.
Mars is farther east from the moon, over halfway up in the southeast. The gap to Jupiter is over 82°.
The Red Planet is marching eastward. Each night it appears farther from Zeta Piscium (ζ Psc on the chart) and closer to dim Pi Piscium (π Psc).
Great Conjunction Countdown: 1 day!
Read about Mars during December.
Detailed note: About mid-twilight (45 minutes after sunset), Jupiter is less than 15° up in the southwest. It is 0.1° (471 arcseconds) below Saturn. Great Conjunction Countdown: 1 day. As the sky darkens further, the thick crescent moon (6.3d, 40%) – about 38° up in the south – is 8.9° to the upper left of δ Aqr. Because of the moon’s brightness, it might be necessary to shield your eyes from the glare to see the starfield. Mars is 35° east of the lunar slice and 82.4° of ecliptic longitude east of Jupiter. The Red Planet is 49° up in the southeast among the dim stars of Pisces. It is moving eastward toward π Psc and away from ζ Psc. This evening it is 2.8° to the upper left of ζ Psc and 4.4° to the upper right of π Psc. Mars passes π Psc early in the new calendar year.
Read more about the planets during December.
April 25, 2021: Mercury passes Evening Star Venus this evening after sunset. Look low in the western sky about 20 minutes after sunset. Mars is marching eastward in Gemini, near the star cluster Messier 35. The bright moon is near Spica.
April 25, 2021: Morning planets Jupiter and Saturn are in the southeast before sunrise. Jupiter is in front of the stars of Aquarius, while Saturn’s starry background is Capricornus.
April 24, 2021: Brilliant Evening Star Venus and bright Mercury are entering the evening sky. They are low in the west-northwest during evening twilight. The bright moon is in the southeast in Virgo. Mars moves into Gemini as it approaches the star cluster Messier 35.
April 24, 2021: The bright gibbous moon is near a star in Virgo during the early morning. From parts of the Western Hemisphere, the moon covers the star. Before sunrise, bright morning planets, Jupiter and Saturn are in the southeast before sunrise.
April 23, 2021: Evening Star Venus and Mercury are entering the evening sky. They are found very low in the west-northwest after sunset. The bright moon is in the southeastern sky during the early evening. Mars is moving toward the star cluster Messier 35.