What are the equinoxes? What is special about these days?

You asked what are the equinoxes.

You know how the Earth's spin axis is tilted over to one side, and how
as we orbit the sun the axis points in a fixed direction? When we're
on one side of our orbit the northern hemisphere leans towards the Sun
and it's summer here, while it's winter in the other hemisphere. When
we're on the other side of our orbit the northern hemisphere is
leaning away from the Sun and experiences its winter.

Well, halfway between summer and winter are the equinoxes. Twice a
year, in spring and again in fall, a line from the center of the Sun
to the center of the Earth passes right through the Equator -- in
other words, if you were standing on the equator, the Sun would be
directly overhead.

Best wishes,
-Neal.

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