The Moon and Mercury will share the same right ascension, with the Moon passing 51' to the north of Mercury. The Moon will be 2 days old.
At around the same time, the two objects will also make a close approach, technically called an appulse.
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 5° above the horizon at dusk.
The Moon will be at mag -9.5, and Mercury at mag 0.2, both in the constellation Leo.
The pair will be a little too widely separated to fit comfortably 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 | 10h04m00s | 12°19'N | Leo | -9.5 | 32'09"2 |
| Mercury | 10h04m00s | 11°27'N | Leo | 0.2 | 7"1 |
The coordinates above are given in J2000.0. The pair will be at an angular separation of 26° from the Sun, which is in Cancer at this time of year.
The sky on 25 Jul 2017
| The sky on 25 July 2017 | ||||||||||||||||||||||||||||||||||
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7% 2 days 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
| 19 Jul 2017 | – Mercury at highest altitude in evening sky |
| 29 Jul 2017 | – Mercury at greatest elongation east |
| 12 Sep 2017 | – Mercury at greatest elongation west |
| 13 Sep 2017 | – Mercury at highest altitude in morning sky |
Image credit
The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.