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The earliest Latin calendar
had only 10 months, with September,
from septem, "seven"; October, November, and December, from octo,
novem, and decem, "eight,", "nine," and
"ten." The Emperor Domitian, also, in imitation of Julius and
Augustus Caesar, gave September and October his own names, Germanicus and
Domitianus; but, on his being slain by treacherous assassins in his home
ames, Germanicus and Domitianus. On his being slain by treacherous
assassins (I loved this line in my research in the Grolier and World Book
Encyclopedias; as if there are any other kind of assassins... mmm...
non-treacherous, friendly assassins, perhaps!) on September 18, A.D. 96,
Germanicus and Domitianus recovered their ancient denominations of
September and October. The sidereal event that distinguishes September
from its neighbors is the presence of the autumnal equinox. If the earth's
axis were perpendicular to the plane of the earth's orbit around the sun,
there would be no change of seasons. Day and night would be of nearly
constant length, and there would be equal conditions of temperature. The
axis tilts 230: 27 prime away from a perpendicular to the orbit, however,
and only in March and September is the axis at right angles to the sun.
These two moments in the year occur when the Sun is exactly over the
equator, and day and night are hence of equal length. This first day of
autumn, or autumnal equinox, occurs about September 23. The first day of
spring, (in the Northern Hemisphere), the vernal, or spring, equinox
occurs about March 21. In the Southern Hemisphere the seasons are
reversed. |