The Moon will pass through the Earth's shadow between 22:27 and 00:00 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 Antarctica, the Americas, Africa and Europe.

It will be visible from Cambridge in the south-eastern sky. The Moon will lie 28° above the horizon at the moment of greatest eclipse.

Maximum eclipse will occur at 23:14 (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 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.

Moreover, on this occasion no more than 11% 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.

Timing

The table below lists the times when each part of the eclipse will begin and end.

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 16 will be visible.

The eclipse geometry

Lunar eclipses occur when the Sun, Earth and Moon are aligned in a straight line, so that the Earth passes between the Sun and Moon and casts a shadow onto the latter's surface.

Each time the Moon orbits the Earth, it passes almost opposite to the Sun in the sky as it reaches Full Moon. If the Moon orbited the Earth in exactly the same plane that the Earth orbits the Sun, the Earth would pass between the Sun and Moon and create a lunar eclipse at Full Moon every month.

In fact, the Moon's orbit is tipped up at an angle of 5° relative to the Earth's orbit around the Sun. This means that the alignment of the Sun—Earth—Moon line at Full Moon usually isn't exact. As a result, an observer on the Moon would see the Earth pass a few degrees to the side of the Sun.

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 this Earth–Sun plane twice each month, at the points on the left and right labelled as nodes. A lunar eclipse happens only when one of these node crossings happens to coincide with Full Moon. This happens roughly once every six months, usually two weeks before or after a solar eclipse.

Further information

This eclipse is a member of Saros series 108. The position of the Moon at the moment of greatest eclipse is as follows:

The coordinates above are given in J2000.0.

Next/previous eclipses

The sky on 21 Nov 2024

Source

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