The Moon will pass last quarter phase, rising in the middle of the night and appearing prominent in the pre-dawn sky.
From San Diego, it will be visible in the morning sky, becoming accessible around 01:14, when it reaches an altitude of 8° above your south-eastern horizon. It will then reach its highest point in the sky at 05:53, 42° above your southern horizon. It will be lost to dawn twilight around 06:14, 41° above your southern horizon.
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.
Observing the Moon at last quarter
Over coming days, the Moon will rise later each day, so that it is visible for less time before sunrise and rises less far above the eastern horizon before dawn. By the time it reaches new moon, it will rise at around dawn and set at around dusk, making it visible only during the daytime.
Its daily progress is charted below, with all times are given in San Diego local time.
|Altitude of Moon
|Direction of Moon
|13 Feb 2017||06:32||19:30||21°||west|
|14 Feb 2017||06:31||20:30||28°||west|
|15 Feb 2017||06:31||21:25||33°||south-west|
|16 Feb 2017||06:31||22:17||37°||south-west|
|17 Feb 2017||06:31||23:13||40°||south-west|
|18 Feb 2017||06:26||00:04||41°||south|
|19 Feb 2017||06:26||00:58||40°||south|
|20 Feb 2017||06:26||01:51||38°||south|
|21 Feb 2017||06:25||02:39||34°||south-east|
|22 Feb 2017||06:25||03:31||28°||south-east|
|23 Feb 2017||06:21||04:15||21°||south-east|
|24 Feb 2017||06:20||05:02||14°||south-east|
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 404,000 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 February 2017|
21 days old
All times shown in PST.
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.
|18 Feb 2017||– Moon at Last Quarter|
|26 Feb 2017||– New Moon|
|05 Mar 2017||– Moon at First Quarter|
|12 Mar 2017||– Full Moon|
Simulated image courtesy of Tom Ruen.