Simulated image courtesy of Tom Ruen.

Moon at Last Quarter

Dominic Ford, Editor
From the Moon feed

Objects: The Moon
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The sky at

The Moon will pass last quarter phase, rising in the middle of the night and appearing prominent in the pre-dawn sky.

From Seattle, it will be visible in the dawn sky, rising at 02:27 (PDT) – 2 hours and 53 minutes before the Sun – and reaching an altitude of 13° above the southern horizon before fading from view as dawn breaks around 05:00.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

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 last quarter, it rises in the middle of the night and appears high in the sky by dawn. It sets at around lunchtime. More information about the Moon's phases is available here.

The exact moment of last quarter

The exact moment of last 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 last quarter moon can be observed at any time in the pre-dawn sky.

At the moment it reaches last quarter, the Moon's distance from the Earth will be 387,000 km. Its celestial coordinates will be as follows:

Object Right Ascension Declination Constellation Angular Size
The Moon 19h47m00s 26°21'S Sagittarius 30'51"

The coordinates above are given in J2000.0.

The sky on 18 October 2021
Sunrise
07:34
Sunset
18:18
Twilight ends
19:58
Twilight begins
05:50

12-day old moon
Waxing Gibbous

98%

12 days old

Planets
Rise Culm. Set
Mercury 06:07 11:57 17:48
Venus 12:02 16:01 20:00
Moon 17:39 --:-- 05:14
Mars 07:13 12:41 18:09
Jupiter 16:06 21:00 01:55
Saturn 15:23 19:56 00:29
All times shown in PDT.

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

15 Apr 2153  –  Moon at Last Quarter
23 Apr 2153  –  New Moon
01 May 2153  –  Moon at First Quarter
08 May 2153  –  Full Moon

Image credit

Simulated image courtesy of Tom Ruen.

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