The Moon and Mercury will share the same right ascension, with the Moon passing 6°31' to the north of Mercury. The Moon will be 1 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 2° above the horizon at dusk.
The Moon will be at mag -9.3, and Mercury at mag 0.0, both in the constellation Virgo.
The pair will be too widely separated to fit within the field of view of a telescope or pair of binoculars, but will be visible to the naked eye.
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 | 12h42m00s | 0°02'S | Virgo | -9.3 | 32'09"7 |
| Mercury | 12h42m00s | 6°33'S | Virgo | 0.0 | 6"4 |
The coordinates above are given in J2000.0. The pair will be at an angular separation of 23° from the Sun, which is in Leo at this time of year.
The sky on 8 Sep 2021
| The sky on 8 September 2021 | ||||||||||||||||||||||||||||||||||
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6% 1 day old |
All times shown in EDT.
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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
| 02 Sep 2021 | – Mercury at highest altitude in evening sky |
| 13 Sep 2021 | – Mercury at greatest elongation east |
| 25 Oct 2021 | – Mercury at highest altitude in morning sky |
| 24 Oct 2021 | – Mercury at greatest elongation west |
Image credit
The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.