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 01:26 (PDT) – 2 hours and 53 minutes before the Sun – and reaching an altitude of 19° above the south-eastern horizon before fading from view as dawn breaks around 03:59.
At this time in its monthly cycle of phases, it appears almost exactly half illuminated.
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 coordinates above are given in J2000.0.
|The sky on 18 October 2021|
12 days old
All times shown in PDT.
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.
|26 May 2171||– Moon at Last Quarter|
|03 Jun 2171||– New Moon|
|11 Jun 2171||– Moon at First Quarter|
|17 Jun 2171||– Full Moon|
Simulated image courtesy of Tom Ruen.