Eclipses of the Moon & Sun

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Learning about Astronomy _____________________________star4me.gif (3183 bytes)

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Eclipse  -
When planetary body blocks the light from the local star (the Sun) and casts a shadow on another planetary body in close orbit.

Penumbra -
The partial light seen from or on the planetary body in eclipse.

Umbra -
The center on the shadow casted by the star.

Totality -
Traveling over the surface of the Earth at 1500 to 2400 km per hour the penumbra measuring 4,400 miles in diameter compared to the umbra of 170 miles in diameter and always traveling East to West. 
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Total Eclipse - A complete blockage of light as seen from another planetary body.

Annular Eclipse -
A Solar Ecilpse that is less than Total due to the Moon being too far from the Earth to the Sun's disc.

Lunar Eclipse -
When the Earth blocks the sun light striking the Moon

Solar Eclipse  -
When the Moon blocks the light striking

Partial Ecilpse  -
Less then a total eclipse were the disc the the Sun can be seen around the silohette of the Moon.

Bailey Beads -
Portions the the Suns disc can be seen as very bright spot just before and after Total Eclipse as the Sun shines through irregularity of the Moon's Terminator.  Named after Francis Baily, the 18th century English amateur astronomer who was the first to draw attention to them.

Solar Corona -
The portion of Sun's upper atmosphere can be seen during Total Eclipse.

Chromosphere -
The lower portion of the Sun's atmosphere that appears as a rosy colored ring during a total eclipse.

Shadow bands -
Result of sunlight being distorted by irregularities in the Earth's atmosphere, and are best observed on an open floor or wall.

Saros Cycle -
Sun and Moon eclipses of the occur in a repeating pattern every 6585.32 days (just over 18 years). Since ancient times this period is called the 'saros', a term first used by Edmund Halley which he took from a Babylonian word.

Prominence -
A gaseous formation above the surface of the Sun and can be seen during a Solar Eclipse.

MORE INFORMATION WILL BE ADDED SOON!

There have been:  Visitors since 11/19/98
This web site was updated on 08/10/99
For additional information contact
Bernie Kluga  President, Mark Simpson VP  , Carol Bates, Treasurer, Nick Beser, Secretary
APL Amateur Astronomy Club, 443-778-7257 or 240-228-7257
Copyright 1996, 1997, 1998,1999 by JHU/APL Amateur Astronomy Club. All rights reserved.