|
What month is it anyway?
by W.Holidays
A
calendar month refers to the common or Gregorian calendar.
April, June, September, and November contain 30 days. The rest have 31 days,
except February. February has 28 days except in the bissextile, or leap year,
when it has 29.
Thirty days hath September,
April, June, and November;
All the rest have thirty-one,
Excepting
February alone
Which hath but twenty-eight, in fine,
'Till leap year
gives it twenty-nine.
A solar month refers to
the time it takes for the sun to pass through one sign of the zodiac and return
to the same zodiac sign.
A lunar month refers to the
time it takes for one revolution of the moon.
Now it really gets
complicated:
-
A synodical month is a
period from one new moon to the next.
-
A nodical month is the
time it takes for one revolution of the moon from one node and to return to the
same node.
-
The sidereal month is
the time it takes for one revolution of the moon from a star and to return to
the same star.
-
The anomalistic month
is the time it takes for one revolution of the moon from perigee and to return
to the same perigee.
-
The tropical month is
the time it takes for the moon to pass from any point of the ecliptic and back
to the ecliptic.
|
