New Moon

2015 Feb 18

Dominic Ford – originally published on In-The-Sky.org

The Moon will pass close to the Sun and become lost in the Sun’s glare for a few days.

The Moon‘s orbital motion carries it around the Earth once every four weeks, and as a result its phases cycle from new moon, through first quarter, full moon and last quarter, back to new moon once every 29.5 days.

This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. Click here for more information about the Moon’s phases.

At new moon, the Earth, Moon and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun’s glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is almost entirely unilluminated.

Over coming days, the Moon will become visible in the late afternoon and dusk sky as a waxing crescent, setting an hour later each evening. By first quarter, in a week’s time, it will be visible until around midnight. The times below are given in London local time:

Date Sun
sets at
Moon
sets at
Altitude of Moon
at sunset
Direction of Moon
at sunset
18 Feb 2015 17:14 16:47 -8° west
19 Feb 2015 17:16 18:10 west
20 Feb 2015 17:18 19:30 14° south-west
21 Feb 2015 17:20 20:49 25° south-west
22 Feb 2015 17:22 22:08 35° south-west
23 Feb 2015 17:23 23:22 44° south-west
24 Feb 2015 17:25 00:32 50° south

At the moment of closest approach, it will pass within 3°22' of the Sun, in the constellation Aquarius. The exact positions of the Sun and Moon will be:

Object Right Ascension Declination Constellation Angular Size
The Moon 22h02m40s -08°23' Aquarius 33'26"
Sun (centre) 22h07m -11°32' Aquarius 32'21"

The coordinates above are given in J2000.0.


The details of this observing event were provided courtesy of In-The-Sky.org

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