Mercury as September Morning Star

Panorama of the eastern sky with Mercury and the Moon as seen from Chicago 30 minutes before sunrise from 2017 AUG 31 to OCT 01 - 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 morning apparition in the eastern sky following its inferior conjunction between Earth and Sun on 2017 AUG 26. This should be a fine apparition except for observers south of the tropics.

   Apparent direct motion in right ascension resumed on 2017 SEP 04. Mercury reached its Greatest Western Elongation of 17.9° on SEP 12. By the standard of 30 minutes before sunrise for Chicago, Mercury achieved its highest altitude of 10.7° on SEP 13. Through a telescope on SEP 13 it appeared in dichotomy, i.e. 50% illuminated like a Half Moon. Prior to that it appeared as a crescent and afterward gibbous. While increasing in brilliance, Mercury will fall to superior conjunction behind the Sun on OCT 09.

NOTE: Event dates in this article are for North American Central Time at those moments nearest to 30 minutes before sunrise 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
New Orion Products!

Please consider supporting this website by disabling your ad-blocking of this site. This site does not use audio ads, popups, or other annoyances. Thank you!

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