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See
explanation above. The vertical axis
rerpesents the angle of the sun measured from north and the horizontal axis is
the sun’s elevation in degrees.
This analemma is for noon, sun time, and would have a slightly different
shape for other times.
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At the equinoxes, when the
sun’s rays are perpendicular to the equator, the declination is defined as
zero. It changes throughout the
year, moving north and south 23.5 degrees – the angle of the tilt in the earth’s
axis. To figure the angle of the
sun at noon on any given day, you add the declination to the latitude. So at the winter solstice, at noon at
the henge, the angle of the sun is (45-23.5) degrees and at the summer solstice
it is 68.5 degrees.
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The equation of time is the
difference between sundial time and clock time. If you check your watch at the moment the sun is highest in
the sky, it varies over the course of the year between 15 minutes slow and 15 minutes fast. This is the same phenomenon as the east
– west component of the analemma’s figure eight.
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| Sunrise and sunset through the year |
