Astronomical Observing, Eclipses, and Photography - Joseph Cali


Partial Eclipse of the Moon - Syzygy at Sunset on November 19th, 2021

On November 19th, 2021, a partial lunar eclipse occurs in the afternoon and early evening.  Half of the eclipse will already be over by the time the Moon rises. In fact maximum eclipse and moon rise are only minutes apart and the remainder of the eclipse occurs during twilight. The eclipse is classed as partial but is very nearly a total eclipse with the Moon grazing the edge of the Earth's umbra much as it did last May where it was classed as a total but one limb remained bright. The eclipse is at greatest eclipse just as the Moon is rising and the sun is setting.  The Moon is going to be very difficult if not impossible to see at this time. the atmosphere will dim the already faint Moon and the sky will still be bright.

There are three  officially named and defined twilights, Civil, Nautical and Astronomical Twilight. An understanding of these will help understand the observation limits.

The brightness of the sky obviously varies during each twilight and  varies depending what part of the sky you are looking at so the following descriptions of sun altitude are accurate but the appearance descriptions are necessarily approximate.
So as time passes and the Moon rises, the twilight sky is continually dimming and at some point, the sunlit crescent of the Moon will become visible and at a later time, the eclipsed (red) part of the Moon may become visible against a darker blue sky.  The Moon may be visible right from moonrise. If you saw the lunar eclipse around sunrise on July 28, 2018, this event will be somewhat similar.  In the photo below, the faint outline of the totally eclipsed Moon is visible setting on the western horizon during the July 2018 eclipse.  

I can't say for sure whether or not it will be visible at moonrise due the the sky brightness.  Even if it's possible to see it as the Moon rises, if  you don't know exactly where to look, you probably won't see it even if it's visible at moonrise.

The Moon rises at an azimuth of 66o east of north at  19h46m eastern daylight time in Canberra. On a magnetic compass, the deviation in and around the ACT varies from 12o - 12.5o  depending where you are observing from around the ACT/NSW border zones. So 66o east of north corresponds to a bearing of about 78.5o magnetic east.

Lunar Eclipse Contacts , Sunset, and twilight times
Eclipse EventContact Label / Description
Time [EDT]
Penumbral Begins P1
Partial Begins
U1 18:18:42.7
Sunset / Moon rise
Bright sky 19:50
Greatest Eclipse
GREATEST 20:02:55.5
 Civil Twilight
Light Blue Sky 20:20
 Nautical Twilight
Dark Blue Sky 20:54
Astronomical Twilight 
Dark Sky 21:32
Partial Ends
U4 21:47:06.9
Penumbral Ends
P4 23:03:43.8

This photo above shows the faint dim red disc of the totally eclipsed setting Moon taken about 20 mins before sunrise and during civil twilight. It gives some indication of how difficult it may be to see the rising eclipsed Moon. On Nov 19, the Moon will have a brighter sunlit white cusp. As the twilight sky darkens and the sunlit crescent grows, the Moon should fairly quickly become easier to identify.  In the table below I have listed in chronological order, the various lunar eclipse phases as well as sunset and moonrise and the twilight times.

No doubt, the click baiters will be out in force with pictures of giant bright red Moons, artificaially perched on various skylines. Don't be fooled, this won't be easy to see but that's the fun of the observing challenge. As the eclipse progresses it will quickly become more visible. 

In the illustration below, I have attempted to depict the lunar visibility
against background sky brightness and colour graphically with estimated brightness of sky background. This is not easy to predict or illustrate even though I have observed many sunrise/sunset lunar eclipses.  The entire event takes place bewteen rise ENE, and end of eclipse NE so make sure you have a good view to the north east!

Good luck and clear skies!