Dominic Ford, Editor
From the Eclipses feed
The Moon will pass through the Earth's shadow between 22:45 and 02:37 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, Oceania, the Americas and Europe.
It will be visible from Cambridge in the southern sky. The Moon will lie 29° above the horizon at the moment of greatest eclipse.
Maximum eclipse will occur at 00:41 (all times given in Cambridge 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.
On this occasion 80% 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 May 15 will be visible.
The table below lists the times when each part of the eclipse will begin and end.
|22:45||02:45||Moon begins to enter the Earth's penumbra|
|02:37||06:37||Moon leaves the Earth's penumbra|
This eclipse is a member of Saros series 111. 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 20 February 2019|
16 days old
All times shown in EST.
Espanak, F., & Meeus, J., Five Millennium Canon of Lunar Eclipses: -1999 to +3000, NASA Technical Publication TP-2009-214172 (2009)
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|15 May 1984||– Full Moon|
|22 May 1984||– Moon at Last Quarter|
|30 May 1984||– New Moon|
|06 Jun 1984||– Moon at First Quarter|