Conjunction between the Moon and Mars

2018 Feb 9

Dominic Ford – originally published on

The Moon and Mars will make a close approach, passing within 4°18′ of each other.

From London (click to change), the pair will be difficult to observe as they will appear no higher than 17° above the horizon. They will be visible in the dawn sky. They will rise at 03:00 (BST), 4 hours and 26 minutes before the Sun, and attain an altitude of 17° above the southern horizon before fading from view as dawn breaks at around 07:02.

At the moment of closest approach, the Moon will be at mag -11.4, and Mars at mag 0.7, both in the constellation Ophiuchus.

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.

The precise positions of the Moon and Mars at the moment of closest approach will be as follows:

Object Right Ascension Declination Constellation Magnitude Angular Size
The Moon 16h29m30s -16°53′ Ophiuchus -11.4 29’39″2
Mars 16h26m00s -21°07′ Ophiuchus 0.7 5″8

The coordinates above are given in J2000.0. The pair will be at an angular separation of 71° from the Sun, which is in Capricornus at this time of year.

The details of this observing event were provided courtesy of