Eclipse Watching

25 YEARS 1985 - 2010	Letchworth & District Astronomical Society
	Eclipse Watch

What is an eclipse?

When the Earth, moon and sun are all perfectly aligned, observers on Earth may be able to witness an eclipse. There are two main types of eclipses; lunar eclipses and solar eclipses.

A lunar eclipse occurs when the Earth lies between the sun and the Moon, and the Earth's shadow falls on the Moon. Anyone on the side of the Earth that faces the Moon at that time can see such an eclipse. If only the outer part of Earth's shadow croses the Moon, then a partial eclipse is seen; if the central part of the shadow covers the Moon, the result is a total eclipse.

A solar eclipse occurs when the Moon lies between the sun and the Earth, and blocks the view of the sun. If the Moon only partially blocks the sun then this causes a partial eclipse; if the Moon completely coves the sun, the result is a total eclipse.

Eclipses are fairly rare events, and there is only one - an eclipse of hte Moon. Unfortunately we'll have to wait until December, it's early in the morning and the Moon sets about 20 minutes after the mamximum point of the eclipse.

So what is going to happen?

The eclipse takes place early on the morning of December 21.

Here is the sequence of events.

05:28	The Moon will begin to enter the outer part of the Earth's shadoe - the penumbra - though this will have very little visual impact. The Moon may begin to appear a little darker just before the Moon enters the umbra.
06:32	The Moon begins to enter the umbra - the darkest part of the Earth's shadow. This phase is clearly visible to the naked eye.
07:40	Totality. By now the moon is completely covered by the umbra. However, in a similar way to the sun appearing darker when it sets, sunlight passing through the Earth's atmosphere and falling on the moon can result in the Moon appearing a dull orange or coppery colour.
08:16	Mid-totality.
08:26	Sun rises. With clear horizons it will be possible to see the sun and th eclipsed Moon at the same time.
08:35	Moon sets.
08:53	Totality ends as the Moon begins to exit the Umbra. It is totally clear by 10:01 and the eclipse ends when it is clear of the penumbra at 11:04.

You can download a file with full details.

How do I take part?

We plan to be on site around 5am. If you would like to join us then let us know that you'd like to come along by sending a message to events-at-ldas.org.uk (Replace "-at-" with "@")

There is no charge for this activity.

We will add further information on this page in early December.

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