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The above chart is copyrighted © 1998 by Earth View Inc and redisplayed with permission.
The chart is part of Earth Views' Introductory Eclipse Tutorial.
A total solar eclipse is the most dramatic of all astronomical events - one that even people who don't usually look upwards can hardly fail to notice.
"The darkness of totality resembles nighttime, and plants and animals react accordingly. Birds stop singing and may go to roost. Daytime flower blossoms begin to close as if for the night. Bees become disoriented and stop flying. The temperature drops in the coolness of the Moon's shadow. All of Nature seems still and quiet for this brief moment of daytime darkness."
A solar eclipse can be seen because of interesting coincidence: both the Sun and the Moon appear to have almost the same diameter as viewed from the Earth. This fortuitous circumstance is because while the Sun is much larger than the Moon, it's also much farther away from the Earth. Keep in mind that both the Sun and the Moon travel along the Ecliptic - that line which serves as an imaginary highway on which along travels the Sun, Moon and most other objects of the Solar System. When the Moon comes directly between the Sun and the Earth, it casts a shadow on the Earth. Although the Moon passes the Sun once every lunar month (about every 28 days) it generally is "above" or "below" the Sun's path, but once or twice every a year or so the Moon and Sun's path coincide and a Solar Eclipse occurs somewhere on the Earth's surface.
The chart above illustrates why a total Solar Eclipse is visible from only a small part of the Earth. The shadow cast by the Moon on the Earth's surface consists of parts the umbra and the penumbra. Parts of the Earth within the penumbra are only partially blocked from the Sun's rays and will experience a partial solar eclipse, while the small section of the Earth that is totally blocked from the Sun is within the umbra and will experience a total eclipse. Because of the movement of the Earth and Moon, the umbra does not stand still but traces a narrow swath along the Earth's surface. The December 4, 2002 Solar Eclipse will be total along a narrow path that will pass from Africa, through the Indian Ocean and finally to Australia. There will be a partial eclipse north and south of this path.
Earth View - the source of both the chart
and the text quoted above.
Central Solar Eclipses: 1991-2030
Exploratorium - Solar Eclipse Resources
Solar Eclipse Photography
Aquarius