Mercury as Autumn Morning Star

Panorama of the eastern sky with Mercury and the Moon as seen from Chicago 30 minutes before sunrise from 2016 SEP 17 to OCT 18 - See article below.

Mercury - Elongations & Altitudes - 2016-17

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

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Elusive Mercury is presenting its autumn morning apparition in the predawn eastern sky following its inferior conjunction between Earth and Sun on 2016 SEP 13. This is a fairly good apparition for observers other than those south of the tropics. This is due to the wide angle at which the ecliptic strikes the horizon at sunrise near the time of the Autumnal Equinox.

   Mercury resumed apparent direct motion in right ascension on 2016 SEP 21. Greatest Western Elongation of  17.9° will be reached on SEP 28. Through a telescope on SEP 28 Mercury will appear in dichotomy, i.e. 50% illuminated like a Half Moon. Prior to that it will appear as a crescent and afterward gibbous. By the standard of 30 minutes before sunrise for Chicago, Mercury will achieve its highest altitude of 10.9° on SEP 29. While increasing in brilliance, it will fall to superior conjunction behind the Sun on OCT 27.

   Mercury will appear near Jupiter on 2016 OCT 11

   The Moon will appear near Mercury on 2016 SEP 29.

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 - 2016-17

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

Mercury Illumination Phase - 2016-17

Graph of the percentage of Mercury’s apparent disk illuminated

Mercury Stellar Magnitude - 2016-17

Graph of the brightness of Mercury measured in stellar magnitude

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© Curt Renz

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