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Solar eclipses
•If you are outside the penumbra you see the whole sun.
•If you are in the penumbra you see only part of the sun.
•If you are in the umbra you cannot see any of the sun.
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•The fact that the moon is just barely big enough to block out the sun results from a coincidence:
•The sun is 400 times bigger than the moon, but also almost exactly 400 times further away.
•The orbit of the moon is elliptical.
•At perigee it can block out the full sun
•At apogee it isn’t quite big enough, giving an annular eclipse.
From our text:  Horizons, by Seeds