Dominic Ford, Editor
From the Eclipses feed
The Moon will pass through the Earth's shadow between 01:25 and 05:03 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 Oceania, the Americas, Portugal and Cape Verde.
It will be visible from Ashburn in the south-western sky. The Moon will lie 31° above the horizon at the moment of greatest eclipse.
Maximum eclipse will occur at 03:14 (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.
Moreover, on this occasion no more than 54% of the Moon's face will pass within the Earth's penumbra, even at the moment of greatest eclipse, making it especially difficult to notice any reduction in the Moon's brightness.
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 17 will be visible.
The table below lists the times when each part of the eclipse will begin and end.
|01:25||05:25||Moon begins to enter the Earth's penumbra|
|05:03||09:03||Moon leaves the Earth's penumbra|
This eclipse is a member of Saros series 148. 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 17 August 2027|
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 Aug 2027, 00:56 EDT||– Moon at First Quarter|
|17 Aug 2027, 03:30 EDT||– Full Moon|
|24 Aug 2027, 22:29 EDT||– Moon at Last Quarter|
|31 Aug 2027, 13:42 EDT||– New Moon|