The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.

Conjunction of the Moon and Mercury

Tue, 23 May 2017 at21:20 EDT(301 days ago)
01:20 UTC

Dominic Ford, Editor
From the Conjunctions feed

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The Moon and Mercury will share the same right ascension, with the Moon passing 1°36' to the south of Mercury. The Moon will be 28 days old.

At around the same time, the two objects will also make a close approach, technically called an appulse.

From Ashburn (click to change) however, the pair will not be observable – they will reach their highest point in the sky during daytime and will be no higher than 6° above the horizon at dawn.

The Moon will be at mag -9.5 in the constellation Cetus, and Mercury at mag 0.1 in the neighbouring constellation of Aries.

The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

A graph of the angular separation between the Moon and Mercury around the time of closest approach is available here.

The positions of the two objects at the moment of conjunction will be as follows:

Object Right Ascension Declination Constellation Magnitude Angular Size
The Moon 02h27m20s +09°37' Cetus -9.5 33'04"9
Mercury 02h27m20s +11°14' Aries 0.1 7"2

The coordinates above are given in J2000.0. The pair will be at an angular separation of 25° from the Sun, which is in Taurus at this time of year.

The sky on 23 May 2017
Twilight ends
Twilight begins

27-day old moon
Waning Crescent


27 days old

Rise Culm. Set
Mercury 04:50 11:29 18:09
Venus 03:49 10:09 16:29
Moon 04:38 11:06 17:35
Mars 06:59 14:27 21:55
Jupiter 16:03 21:54 03:48
Saturn 21:56 02:47 07:34
All times shown in EDT.


The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

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23 Nov 2017, 21:22 EST  –  Mercury at greatest elongation east

Image credit

The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.




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