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Equation of time and
length of solar day
The
Equation of Time is the
difference between the time determined by a sundial and the clock time.
It is due to the obliquity of the Earth's axis and the unequal motion
of the Earth around the Sun (ellipse). The value, computed for 12:00
UT, is between -14 :20 min (near Feb 12) and +16:24 min (near Nov 4).
 Diagram by my Planets Applet (using
"Write/Draw" menu)
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Sun Declination
& Equation of Time
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The
length of the
current solar day (i.e. the time
interval between culmination of the Sun on prev. and curent day) is not
exactly 24 hours; the difference is given in brackets (e.g. +18.8 s).
For
2001:
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equation of time
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length of solar day
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Jan 1
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- 03:45 min
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24 h - 28.3 s
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15
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- 09:34 min
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24 h - 21.2 s
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Feb 1
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- 13:38 min
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24 h - 08.1 s
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15
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- 14:07 min
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24 h + 02.8 s
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Mar 1
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- 12:18 min
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24 h + 11.6 s
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15
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- 08:51 min
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24 h + 16.8 s
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Apr 1
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- 03:48 min
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24 h + 17.9 s
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15
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+ 00:02 min
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24 h + 14.6 s
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May 1
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+ 02:57 min
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24 h + 07.3 s
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15
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+ 03:40 min
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24 h - 00.6 s
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Jun 1
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+ 02:09 min
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24 h - 09.1 s
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15
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- 00:31 min
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24 h - 12.8 s
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Jul 1
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- 03:53 min
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24 h - 11.6 s
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15
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- 05:59 min
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24 h - 06.2 s
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Aug 1
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- 06:18 min
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24 h + 03.6 s
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15
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- 04:24 min
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24 h + 11.7 s
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Sep 1
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+ 00:06 min
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24 h + 18.9 s
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15
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+ 04:55 min
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24 h + 21.4 s
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Oct 1
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+ 10:26 min
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24 h + 19.4 s
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15
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+ 14:17 min
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24 h + 13.4 s
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Nov 1
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+ 16:24 min
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24 h + 01.7 s
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15
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+ 15:20 min
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24 h - 10.0 s
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Dec 1
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+ 10:50 min
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24 h - 22.3 s
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15
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+ 04:41 min
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24 h - 28.8 s
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Equation of
Time table by my Planets Applet
(use "Write/Draw" menu")
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