The Moon and Mercury will make a close approach, passing within a mere 1.7 arcminutes of each other. From some parts of the world, the Moon will pass in front of Mercury, creating a lunar occultation. The Moon will be 28 days old.
From Los Angeles , the pair will be visible in the dawn sky, rising at 05:23 (PDT) – 1 hour and 13 minutes before the Sun – and reaching an altitude of 11° above the eastern horizon before fading from view as dawn breaks at around 06:20.
The Moon will be at mag -8.4; and Mercury will be at mag -1.0. Both objects will lie in the constellation Leo.
They 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.
At around the same time, the pair will also share the same right ascension – called a conjunction.
A graph of the angular separation between the Moon and Mercury around the time of closest approach is available here.
The positions of the pair at the moment of closest approach will be as follows:
| Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
| The Moon | 10h49m20s | 9°05'N | Leo | -8.4 | 31'34"9 |
| Mercury | 10h49m30s | 9°06'N | 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 Sep 2017
| The sky on 18 September 2017 | ||||||||||||||||||||||||||||||||||
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0% 28 days old |
All times shown in PDT.
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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
| 13 Sep 2017 | – Mercury at highest altitude in morning sky |
| 23 Nov 2017 | – Mercury at greatest elongation east |
| 27 Nov 2017 | – Mercury at highest altitude in evening sky |
| 29 Dec 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.