The Moon and Mercury will share the same right ascension, with the Moon passing 1°52' to the north of Mercury. The Moon will be 28 days old.
From Cambridge however, the pair will not be observable – they will reach their highest point in the sky during daytime and will be no higher than 7° above the horizon at dawn.
The Moon will be at mag -8.6, and Mercury at mag 0.5, both in the constellation Libra.
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 | 15h41m40s | 15°02'S | Libra | -8.6 | 30'40"5 |
| Mercury | 15h41m40s | 16°55'S | Libra | 0.5 | 8"5 |
The coordinates above are given in J2000.0. The pair will be at an angular separation of 17° from the Sun, which is in Ophiuchus at this time of year.
The sky on 5 Dec 2018
| The sky on 5 December 2018 | ||||||||||||||||||||||||||||||||||
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0% 28 days old |
All times shown in EST.
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Warning
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.
Source
The circumstances of this event were computed using the DE430 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
| 10 Nov 2018 | – Mercury at highest altitude in evening sky |
| 13 Dec 2018 | – Mercury at highest altitude in morning sky |
| 15 Dec 2018 | – Mercury at greatest elongation west |
| 26 Feb 2019 | – 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.