Dominic Ford, Editor
From the Eclipses feed
There will be a penumbral eclipse of the Moon, though it will not be visible from Ashburn since the Moon will be beneath the horizon at the time.
The eclipse will last from 12:55 until 16:54, and maximum eclipse will occur at 14:55 (all times given in Ashburn time).
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 begin to dim, as it is less strongly illuminated by the Sun, but the whole of the Sun's disk will remain illuminated to some degree.
Although the Moon's light dims considerably during a penumbral eclipse, this is only perceptible to those with very astute vision, or in carefully controlled photographs.
This is a rare occasion when the whole of the Moon's face will pass within the Earth's penumbra, and so the reduction of the Moon's brightness will be more perceptible than usual. Such events are called total penumbral lunar eclipses, and are rare because the statistical chance that the Moon will enter the Earth's umbra at some point is very high once it has passed fully within its penumbra, and this makes an eclipse a partial lunar eclipse.
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 September 16 will be visible.
The table below lists the times when each part of the eclipse will begin and end.
|12:55||16:55||Moon begins to enter the Earth's penumbra|
|16:54||20:54||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 2016|
15 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)
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|09 Sep 2016, 07:50 EDT||– Moon at First Quarter|
|16 Sep 2016, 15:06 EDT||– Full Moon|
|23 Sep 2016, 05:57 EDT||– Moon at Last Quarter|
|30 Sep 2016, 20:13 EDT||– New Moon|