Dominic Ford, Editor
From the Eclipses feed
The Moon will pass through the Earth's shadow between 21:44 and 01:18 EDT, creating a penumbral lunar eclipse. The eclipse will be visible any location where the Moon is above the horizon at the time, including from Africa, the Americas, Europe, French Polynesia and Turkey.
It will be visible from Fairfield in the south-eastern sky. The Moon will lie 34° above the horizon at the moment of greatest eclipse.
Maximum eclipse will occur at 23:31 (all times given in Fairfield time).
The simulation to the right shows Moon's path relative to the Earth's shadow. The outer grey circle is the Earth's penumbra, within which the Earth blocks part of the Sun's light, making the Moon appear less bright than usual, but not completely dark. The inner black circle is the umbra, within which the Earth entirely blocks the Sun's light, and where the Moon's disk would appear entirely unilluminated.
By default the eclipse is drawn with the local vertical in Fairfield uppermost (Zenith up), so that it is orientated as you would see it looking up at the Moon. The compass shows the direction of celestial north relative to the local vertical. Alternatively, you can orientate the sky with celestial north orientated uppermost, by selecting the option North up.
Selecting the option Diagram of Moon's path produces a static display of the Moon's path over the duration of the eclipse.
The lower panel of the simulation shows the Sun's position relative to the horizon as seen from Fairfield.
A penumbral eclipse
Like other lunar eclipses, penumbral eclipses occur whenever the Earth passes between the Moon and Sun, such that it obscures the Sun's light and casts a shadow onto the Moon's surface. But unlike other kinds of eclipses, they are extremely subtle events to observe.
In a penumbral eclipse the Moon passes through an outer region of the Earth's shadow called the penumbra. This is the outer part of the Earth's shadow, in which the Earth appears to cover part of the Sun's disk, but not all of it (see diagram below). As a result, the Moon's brightness will be reduced, as it is less strongly illuminated by the Sun, but the whole of the Moon's disk will remain illuminated to some degree.
The effect is only perceptible to those with very astute vision, or in carefully controlled photographs.
On this occasion 70% of the Moon's face will pass within the Earth's penumbra at the moment of greatest eclipse, and so a modest reduction in the Moon's brightness may be perceptible.
The eclipse geometry
Lunar eclipses occur when the Sun, Earth and Moon are aligned in an almost exact straight line, with the Earth in the middle, such that the Earth casts a shadow onto the Moon. The diagram to the right shows this geometry, though for clarity the Moon is drawn much closer to the Earth than it really is.
The Moon passes close to this configuration every month, when it is at full moon, but because the Moon's orbit around the Earth is tipped up by 5° relative to the Earth's orbit around the Sun, the alignment of the three bodies into a straight line usually isn't exact.
In the diagram to the right, the grid represents the plane of the Earth's orbit around the Sun. As it circles the Earth, the Moon passes through the Earth–Sun plane twice each month, at the points on the left and right labelled as nodes. A lunar eclipse results when one of these node crossings happens to coincide with full moon, which happens roughly once every six months.
Visibility of the eclipse
Eclipses of the Moon are visible anywhere where the Moon is above the horizon at the time. Since the geometry of lunar eclipses requires that the Moon is directly opposite the Sun in the sky, the Moon can be seen above the horizon anywhere where the Sun is beneath the horizon.
The map below shows where the eclipse of August 25 will be visible.
The table below lists the times when each part of the eclipse will begin and end.
|21:44||01:44||Moon begins to enter the Earth's penumbra|
|01:18||05:18||Moon leaves the Earth's penumbra|
This eclipse is a member of Saros series 147. The exact position of the Moon at the moment of greatest eclipse is as follows:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 16 September 2019|
17 days old
All times shown in EDT.
Espanak, F., & Meeus, J., Five Millennium Canon of Lunar Eclipses: -1999 to +3000, NASA Technical Publication TP-2009-214172 (2009)
You may embed the map above in your own website. It is licensed under the Creative Commons Attribution 3.0 Unported license, which allows you to copy and/or modify it, so long as you credit In-The-Sky.org.
You can download it from:
|18 Aug 1980||– Moon at First Quarter|
|25 Aug 1980||– Full Moon|
|01 Sep 1980||– Moon at Last Quarter|
|09 Sep 1980||– New Moon|