© Collin Grady from Las Vegas, Nevada.

Partial lunar eclipse

Sat, 16 Aug 2008 at17:11 EDT(3477 days ago)
21:11 UTC

Dominic Ford, Editor
From the Eclipses feed

Time:       Altitude: °      Azimuth: °

A simulation of how the eclipse will appear from Ashburn.

The outer grey circle is the Earth's penumbra, and the inner black circle is the umbra. Any part of the Moon which passes within the black circle will be unilluminated, while any part within the grey circle will appear less bright than usual.

There will be a partial 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 15:37 until 18:45, and maximum eclipse will occur at 17:11, when 81% of the Moon's disk will lie in shadow (all times given in Ashburn time).

Eclipses of the Moon are easy to watch with the unaided eye. A modest pair of binoculars will give a superb view of the Moon's surface, but are not required. Unlike solar eclipses, lunar eclipses are entirely safe to look at without the need to look through any kind of filter.

They 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. The circular shadow cast by the Earth appears as a bite taken out of the Moon during its partial phases.

Sequence of events

The eclipse will begin at 14:26, when the Moon first enters a region of the Earth's shadow called the penumbra. In this outer part of the Earth's shadow, an observer on the Moon would see the Sun partially obscuring the Sun's disk, but not completely covering it. As a result the Moon's brightness will begin to dim, as it is less strongly illuminated by the Sun, but it remains illuminated.

At 15:37, the edge of the Moon's disk will enter the Earth's umbra. This is the region of space in which an observer on the Moon's surface would see the Earth completely obscuring the whole of the Sun's disk, and would find themselves suddenly thrust into darkness.

As an increasing fraction of the Moon's face creeps into the Earth's umbra, it will appear to have a growing bite taken out of it. We will see our planet's circular shadow sweep across the face of the Moon.

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

14:2618:26Moon begins to enter the Earth's penumbra
15:3719:37Moon begins to enters the Earth's umbra. Partial eclipse begins.
17:1121:11Greatest eclipse
18:4522:45Moon fully outside the Earth's umbra. Partial eclipse ends.
19:5623:56Moon leaves the Earth's penumbra
The geometry of a lunar eclipse
The geometry of a lunar eclipse. Within the penumbra, the Earth covers some fraction of the Sun's disk, but not all of it. In the umbra, the Earth covers the entirity of the Sun's disk. Any parts of the Moon's surface that lie within the Earth's umbra will appear unilluminated. Image courtesy of F. Sogumo.

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.

Map of where the eclipse of August 2008 will be visible.
Map of where the eclipse of August 2008 will be visible. Click here to expand.

Further information

This eclipse is a member of Saros series 138. The exact position of the Moon at the moment of greatest eclipse is as follows:

Object Right Ascension Declination Constellation Angular Size
The Moon 21h45m -12°56' Capricornus 30'41"

The coordinates above are given in J2000.0.

The sky on 22 February 2018
Sunrise 06:51
Sunset 17:53
Twilight ends
Twilight begins

7-day old moon
Age of Moon
7 days

All times shown in EST.
Rise Culm. Set
Mercury 07:11 12:41 18:11
Venus 07:25 13:04 18:43
Moon 10:58 17:50 00:42
Mars 02:15 07:00 11:45
Jupiter 00:18 05:22 10:27
Saturn 03:43 08:28 13:14


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:

Related news

08 Aug 2008, 16:22 EDT  –  Moon at First Quarter
16 Aug 2008, 17:18 EDT  –  Full Moon
23 Aug 2008, 19:51 EDT  –  Moon at Last Quarter
30 Aug 2008, 15:59 EDT  –  New Moon

Image credit

© Collin Grady from Las Vegas, Nevada.




Color scheme