Simulated image courtesy of Tom Ruen.

Moon at First Quarter

Dominic Ford, Editor
From the Moon feed

Objects: The Moon
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The sky at

The Moon will pass first quarter phase, appearing prominent in the evening sky and setting in the middle of the night.

From Washington , it will be visible from soon after it rises, at 12:35, until soon before it sets at 00:40.

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At this time in its monthly cycle of phases, it appears almost exactly half illuminated.

The Moon orbits the Earth once every four weeks, causing its phases to cycle through new moon, first quarter, full moon, last quarter, and back to new moon once every 29.5 days.

As it progresses through this cycle, it is visible at different times of day. At first quarter, it appears high in the sky at sunset before sinking towards the horizon and setting in the middle of the night. More information about the Moon's phases is available here.

Observing the Moon at first quarter

Over coming days, the Moon will set later each day, becoming visible for more of the night. Within a few days, it will not make it very far above the eastern horizon before nightfall. By the time it reaches full phase, it will be visible for much of the night, rising at around dusk and setting at around dawn.

Its daily progress is charted below, with all times are given in Washington local time.

Date Sun
sets at
Moon
sets at
Altitude of Moon
at sunset
Direction of Moon
at sunset
29 Dec 201917:2419:5622°south-west
30 Dec 201917:2420:5630°south-west
31 Dec 201917:2521:5437°south
01 Jan 202017:2622:5142°south
02 Jan 202017:2623:4746°south
03 Jan 202017:2700:4349°south-east
04 Jan 202017:2801:3949°south-east
05 Jan 202017:2902:3746°south-east
06 Jan 202017:3003:3742°east
07 Jan 202017:3104:3936°east
08 Jan 202017:3205:4228°east
09 Jan 202017:3206:4519°east

The exact moment of first quarter

The exact moment of first quarter is defined as the time when the Moon's ecliptic longitude is exactly 90° away from the Sun's ecliptic longitude, as observed from the center of the Earth. However, the Moon does not appear in any way special at this instant in time, and a first quarter moon can be observed at any time in the evening sky.

At the moment it reaches first quarter, the Moon's distance from the Earth will be 403,000 km. Its celestial coordinates will be as follows:

Object Right Ascension Declination Constellation Angular Size
The Moon 00h52m10s 0°07'S Cetus 29'34"

The coordinates above are given in J2000.0.

The sky on 2 Jan 2020

The sky on 2 January 2020
Sunrise
07:45
Sunset
17:27
Twilight ends
19:01
Twilight begins
06:12

7-day old moon
Waxing Gibbous

54%

7 days old

Planets
Rise Culm. Set
Mercury 07:35 12:16 16:58
Venus 09:56 15:03 20:10
Moon 12:27 18:31 00:43
Mars 04:35 09:35 14:35
Jupiter 07:28 12:16 17:03
Saturn 08:25 13:18 18:11
All times shown in MST.

Source

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.

Related news

02 Jan 2020  –  Moon at First Quarter
10 Jan 2020  –  Full Moon
17 Jan 2020  –  Moon at Last Quarter
24 Jan 2020  –  New Moon

Image credit

Simulated image courtesy of Tom Ruen.

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37.13°N
113.51°W
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