Mercury as November Evening Star

Panorama of the western sky with Mercury and the Moon as seen from Chicago 30 minutes after sunset from 2017 OCT 31 to DEC 09 - See article below.

Mercury - Elongations & Altitudes - 2017-18

The planet’s elongations from the Sun and altitudes above the horizon as viewed from latitude N 42°

Mercury 02 Mercury 03 Mercury 04


Elusive Mercury is presenting its evening apparition in the western sky following its superior conjunction behind the Sun on 2017 OCT 08. This is not a good apparition for observers north of the tropics, since at sunset around this time of year the ecliptic strikes the western horizon at a sharp angle.

   Mercury will attain its Greatest Eastern Elongation of 22.0° on 2017 NOV 23. Through a telescope on NOV 27 it will appear in dichotomy, i.e. 50% illuminated like a Half Moon. Prior to that it will appear gibbous and afterward as a crescent. By the standard of 30 minutes after sunset for Chicago, Mercury will reach its highest altitude of 5.4° on NOV 28. Apparent retrograde motion in right ascension will begin on DEC 02. While decreasing in brilliance, Mercury will fall to inferior conjunction between Earth and Sun on DEC 12.

   Mercury will appear near Saturn on 2017 DEC 06.

   The Moon last appeared near Mercury on 2017 NOV 20.

NOTE: Event dates in this article are for North American Central Time at those moments nearest to 30 after sunset for Chicago.

Mercury Angular Diameter - 2017-18

Graph of the apparent angular diameter of Mercury measured in arcseconds  -  Distance in AU = 6.68 / angular diameter

Mercury Illumination Phase - 2017-18

Graph of the percentage of Mercury’s apparent disk illuminated

Mercury Stellar Magnitude - 2017-18

Graph of the brightness of Mercury measured in stellar magnitude

Mercury 05


© Curt Renz

Mercury 01
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Mercury Transit

Mercury Transits Sun - 2019 NOV 11

Previews of the apparent path of Mercury across the Sun Geocentric view and as seen from various cities