Mercury and Mars will share the same right ascension, with Mercury passing 18' to the north of Mars.
At around the same time, the two objects will also make a close approach, technically called an appulse.
From South El Monte however, the pair will not be observable – they will reach their highest point in the sky during daytime and will be no higher than 6° above the horizon at dusk.
Mercury will be at mag -0.2, and Mars at mag 1.8, both in the constellation Cancer.
The pair 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.
A graph of the angular separation between Mercury and Mars 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 |
| Mercury | 08h11m20s | 21°33'N | Cancer | -0.2 | 6"4 |
| Mars | 08h11m20s | 21°14'N | Cancer | 1.8 | 3"6 |
The coordinates above are given in J2000.0. The pair will be at an angular separation of 22° from the Sun, which is in Gemini at this time of year.
The sky on 27 Sep 2025
| The sky on 27 September 2025 | ||||||||||||||||||||||||||||||||||
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37% 6 days old |
All times shown in PDT.
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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.
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| 24 Oct 1973 | – Mars at opposition |
Image credit
The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.