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Conjunction of the Moon and Mercury

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 3°42' to the north of Mercury. The Moon will be 28 days old.

From Cambridge, the pair will be difficult to observe as they will appear no higher than 8° above the horizon. They will be visible in the dawn sky, rising at 05:45 (EDT) – 1 hour and 22 minutes before the Sun – and reaching an altitude of 8° above the south-eastern horizon before fading from view as dawn breaks around 06:46.

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The Moon will be at mag -9.1, and Mercury at mag -0.2, both in the constellation Sagittarius.

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 18h55m10s -18°47' Sagittarius -9.1 30'06"0
Mercury 18h55m10s -22°30' Sagittarius -0.2 6"0

The coordinates above are given in J2000.0. The pair will be at an angular separation of 23° from the Sun, which is in Capricornus at this time of year.

The sky on 25 January 2017
Twilight ends
Twilight begins

27-day old moon
Waning Crescent


27 days old

Rise Culm. Set
Mercury 05:43 10:18 14:52
Venus 08:59 14:54 20:49
Moon 05:08 09:58 14:49
Mars 09:19 15:17 21:16
Jupiter 23:12 04:51 10:27
Saturn 04:21 08:58 13:35
All times shown in EST.


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.

Related news

19 Jan 2017  –  Mercury at greatest elongation west
07 Feb 2017  –  Mercury at aphelion
06 Mar 2017  –  Mercury at superior solar conjunction
23 Mar 2017  –  Mercury at perihelion

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