Conjunction between the Moon and Neptune

2017 Oct 30

Dominic Ford – originally published on

The Moon and Neptune will make a close approach, passing within 0°50' of each other.

From London (click to change), the pair will be visible in the evening sky. They will become visible at around 16:59 (BST) as the dusk sky fades, 16° above your south-eastern horizon. They will then reach its highest point in the sky at 20:15, 30° above your southern horizon. They will continue to be observable until around 00:43, when they sink to 8° above your south-western horizon.

At the moment of closest approach, the Moon will be at mag -12.4, and Neptune at mag 7.9, both in the constellation Aquarius.

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 a through pair of binoculars.

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

Object Right Ascension Declination Constellation Magnitude Angular Size
The Moon 22h53m40s -08°57' Aquarius -12.4 30'57"2
Neptune 22h52m30s -08°10' Aquarius 7.9 2"3

The coordinates above are given in J2000.0. The pair will be at an angular separation of 123° from the Sun, which is in Virgo at this time of year.

The details of this observing event were provided courtesy of