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To: Norman Bates
I hardly think an extrememly rare form of eclipse, one that has not happened since 1987, only began happening in 1103, will only next happen in 2023 and will happen for the last time in 2528,

Where did you see that such an eclipse never happened before 1103 and will never happen agin after 2528?

The moon casts a shadow where it block sunlight. When the moon goes between the Sun and the Earth (which happens twice a year), that shadow extends towards the Earth. The umbra (the part of the shadow where all sunlight is completely blocked) forms a cone. If the tip of the cone hits the earth's surface, those areas covered by the umbra see a "total" eclipse, where the sun is completely blocked for a period of time that can be a split second or as long as over 7 minutes. But the distance between the Earth and the moon varies, and sometimes the tip of the umbral cone does not extend all the way to the Earth's surface. In such a case people directly under the cone tip see an "annular" eclipse, where the moon's shadow forms a disk smaller than the Sun, and so a ring of the Sun's surface can be seen around the (completely dark) image of the moon.

During any kind of eclipse, the movement of both the Earth and the moon cause the moon's shadow to sweep in an arc across the Earth. In this particular case, the distance between the Earth and the moon is such that the umbral tip is above the Earth's surface at the beginning and end of the eclipse's track, but touches the Earth during the middle of it; thus, it is an annular eclipse in the beginning, becomes total in the middle, and reverts to annular at the end.

I am unaware of any assertion by anyone that in the Earth/moon system's 3.6 billion or so year history this kind of interaction never occurred before 1103 and will never happen again after 2528. What's your source for this?

32 posted on 04/07/2005 12:55:17 PM PDT by RonF
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To: RonF

See post 16.


34 posted on 04/07/2005 1:00:40 PM PDT by Norman Bates (In memoriam: Pope John Paul II , Theresa Marie Schindler )
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