A solar eclipse occurs when the Moon blocks our view of the Sun.
It happens when the Moon is exactly between the Earth and the
Sun. By a strange coincidence the Moon is 400 times smaller than
the Sun but also 400 times closer. This results in their angular
size being about the same, allowing the Moon to completely block
the Sun at times. But the Moon’s orbit is not perfectly circular
so sometimes the Moon is farther from the Earth and at other
times it is closer. When the Moon is farthest from the Earth it
is said to be at apogee. When at apogee during a solar eclipse,
the Moon will appear slightly smaller than the Sun and will not
cover it completely, and a ring of Sun will remain visible. This
is called an annular solar eclipse from the Latin word annulus,
meaning ring. The Moon was at apogee during the annular eclipse
of 1994. I took this picture of that event through a special
solar filter attached to a telescope. Using such a filter is the
only safe way to directly view the Sun. Sun glasses are NOT SAFE