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 Fairfield, it will be visible in the morning sky, becoming accessible around 01:23, when it reaches an altitude of 7° above your south-eastern horizon. It will then reach its highest point in the sky at 05:45, 34° above your southern horizon. It will be lost to dawn twilight around 06:56, 32° above your southern horizon.

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 393,000 km. Its celestial coordinates will be as follows:

Object Right Ascension Declination Constellation Angular Size
The Moon 13h57m30s 14°23'S Virgo 30'20"

The coordinates above are given in J2000.0.

The sky on 17 October 2021
Sunrise
07:05
Sunset
18:09
Twilight ends
19:41
Twilight begins
05:33

11-day old moon
Waxing Gibbous

93%

11 days old

Planets
Rise Culm. Set
Mercury 05:53 11:45 17:36
Venus 11:16 15:42 20:09
Moon 17:16 22:58 04:52
Mars 06:51 12:27 18:03
Jupiter 15:40 20:48 01:56
Saturn 14:52 19:43 00:35
All times shown in EDT.

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

22 Jan 2006  –  Moon at Last Quarter
29 Jan 2006  –  New Moon
05 Feb 2006  –  Moon at First Quarter
12 Feb 2006  –  Full Moon

Image credit

Simulated image courtesy of Tom Ruen.

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Fairfield

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41.14°N
73.26°W
EDT

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