8
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.
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 isnt quite big enough, giving an annular eclipse.
From our text:
Horizons, by Seeds