Astronomical importance of the Equinox

As the Earth rotates into and out of its own orbital shadow to face the
Sun,the axial longitudes cut the Earth's orbital orientation at
different angles throughout its annual orbit.



http://honolulu.hawaii.edu/distance/...ams/p4/415.GIF

The Equinox has a special astronomical significance and especially
within the next few weeks as orbital orientation aligns with fixed
axial longitudes at dawn and dusk.

While the axial distortion is at its greatest at the Equinox -

http://homepage.mac.com/tarashnat/as.../0001-08a.jpeg

It does generate a window of opportunity at dawn and dusk on the
Equinox when axial and orbital orientation align to enjoy the
perspective of indepedent orbital motion alone without the infection of
the stellar circumpolar illusion genberated by axial rotation.

In short,twice a year we get to appreciate a direct view of our own
orbital direction around the Sun and around the Milky Way axis.