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 unilluminated.
Over coming days, the Moon will rise and set an hour later each day, becoming visible in the late afternoon and dusk sky as a waxing crescent which sets soon after the Sun. By first quarter, in a week's time, it will be visible until around midnight.
Its day-by-day progress is charted below, with all times are given below in Fairfield local time.
|Altitude of Moon
|Direction of Moon
|17 Jan 2018||16:49||16:50||0°||south-west|
|18 Jan 2018||16:51||17:42||7°||south-west|
|19 Jan 2018||16:52||18:37||16°||south-west|
|20 Jan 2018||16:53||19:33||25°||south-west|
|21 Jan 2018||16:54||20:30||33°||south-west|
|22 Jan 2018||16:55||21:28||41°||south-west|
|23 Jan 2018||16:57||22:27||47°||south|
At the moment of closest approach, it will pass within 1°37'of the Sun, in the constellation Sagittarius. The exact positions of the Sun and Moon will be:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 16 January 2018|
29 days old
All times shown in EST.
Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.
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.
|16 Jan 2018||– New Moon|
|24 Jan 2018||– Moon at First Quarter|
|30 Jan 2018||– The Moon at perigee|
|31 Jan 2018||– Full Moon|
Simulated image courtesy of Tom Ruen.