birding-aus

sunrise and sunset times

To: "Birding-Aus" <>
Subject: sunrise and sunset times
From: "Paul Taylor" <>
Date: Fri, 8 Feb 2002 00:04:11 +1100
> I have been recording sunrise and sunset times from the newspaper for
> Victoria during spring and summer.  In the weeks prior to the longest
> day (summer solstice, 21 or 22 Dec) the daylight hours (or photoperiod)
> of any given day begin and end earlier by the clock than on a day with
> the same number of daylight hours (same length photoperiod) that falls
> the same number of days after the summer solstice that the given day
> does before the solstice.  I hope that sentence is clear.
> Does anybody know why this is so?

In short, the tilt of the Earth's axis means that we see the Sun from
a different each day.  This page has the full details (note that the
diagrams are for Chicago, but the principle applies to where ever you
happen to be on Earth.)

http://homepage.mac.com/jk8/analemma/page2.html


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   Paul Taylor                                  Veni, vidi, tici -
                           I came, I saw, I ticked.


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