Conjunction between the Moon and Mars

2018 Oct 18

Dominic Ford – originally published on

The Moon and Mars will make a close approach, passing within 1°54' of each other.

From London (click to change), the pair will be difficult to observe as they will appear no higher than 18° above the horizon. They will be visible in the evening sky. They will become visible at around 18:21 (BST) as the dusk sky fades, 14° above your south-eastern horizon. They will then reach its highest point in the sky at 20:19, 18° above your southern horizon. They will continue to be observable until around 23:27, when they sink to 7° above your south-western horizon.

At the moment of closest approach, the Moon will be at mag -12.1, and Mars at mag -1.4, both in the constellation Capricornus.

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 21h06m20s -17°40' Capricornus -12.1 29'34"1
Mars 21h07m50s -19°32' Capricornus -1.4 13"4

The coordinates above are given in J2000.0. The pair will be at an angular separation of 108° from the Sun, which is in Virgo at this time of year.

The details of this observing event were provided courtesy of