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

Mon, 18 Sep 2017 at19:23 EDT(121 days ago)
23:23 UTC

Dominic Ford, Editor
From the Conjunctions feed

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The sky at

The Moon and Mercury will share the same right ascension, with the Moon passing 0°01' 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), the pair will be difficult to observe as they will appear no higher than 11° above the horizon. They will be visible in the dawn sky, rising at 05:35 (EST) – 1 hour and 20 minutes before the Sun – and reach an altitude of 11° above the eastern horizon before fading from view as dawn breaks at around 06:38.

The Moon will be at mag -8.4, and Mercury at mag -1.0, both in the constellation Leo.

The pair will be close enough to fit within the field of view of a telescope, but will also 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 10h49m30s +09°04' Leo -8.4 31'34"9
Mercury 10h49m30s +09°06' Leo -1.0 6"0

The coordinates above are given in J2000.0. The pair will be at an angular separation of 15° from the Sun, which is in Virgo at this time of year.

The sky on 18 September 2017
Sunrise 06:53
Sunset 19:12
Twilight ends
Twilight begins

28-day old moon
Age of Moon
28 days

All times shown in EDT.
Rise Culm. Set
Mercury 05:33 12:06 18:40
Venus 04:34 11:21 18:07
Moon 05:13 11:51 18:29
Mars 05:25 12:00 18:34
Jupiter 09:19 14:53 20:27
Saturn 13:54 18:40 23:27


Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.


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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01 Jan 2018, 19:40 EST  –  Mercury at greatest elongation west
15 Mar 2018, 06:18 EDT  –  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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