Other Phenomenon

Have you ever looked at a rise and set time chart of the sun and noticed that in the summer the earliest sunrise and latest sunset do not occur on the longest day of the year? Or that in the winter the latest sunrise and earliest sunset do not occur on the shortest day of the year? This phenomenon is directly related to the shape of the analemma.

Observe the movie by sliding the control at the bottom of the window.

As you look at these pictures, keep in mind two things; the shape of the analemma has been somewhat exaggerated in its width so as to better see this demonstration, and, as in the previous pages, you, the observer, are standing on the equator.

The movie demonstrates where the analemma would appear if we observe it at other times of the day. While it appears that the analemma is rotating to the west, it is actually the Earth that is rotating to the east.

Note carefully the view from the right hand frame. Here, we are standing on the equator, but facing due west. Furthermore, note the position of the analemma around 6:00 p.m. It appears that it’s lying on its side.

Observe the movie by sliding the control at the bottom of the window.

The movie demonstrates what happens if we change our position on the Earth, while observing the analemma at the same time. The analemma is tipped an amount equal to our latitude. A curious event happens at the North Pole, however. As soon as we cross the North Pole, our direction reverses from west to east and the time of day changes from evening to morning! Just the opposite effect happens at the South Pole.
The next picture and movie demonstrate the effect of the analemma on sunrise and sunset time if you are standing at 41.5° North Latitude (a small latitude taken by the author...). The movie takes a small portion of the analemmic curve around the time of the summer and winter solstices. Hopefully, it will become apparent why latest and earliest sunrise and sunset times do not occur at the solstices.

Again, observe the movie by sliding the control at the bottom of the window.

The differences between the times of the solstices and rise and set times becomes more exaggerated the closer we are to the equator. In reverse, at either pole, the analemma has no effect on sunrise and sunset times.

By downloading and running the SunGraph application, you can see the effect of the analemma on rise and set times almost anywhere on Earth.

Time Zone Maps

(688K file size).

(224K file size).

	Observe the movie by sliding the control at the bottom of the window.


	As you look at these pictures, keep in mind two things; the shape of the analemma has been somewhat exaggerated in its width so as to better see this demonstration, and, as in the previous pages, you, the observer, are standing on the equator. The movie demonstrates where the analemma would appear if we observe it at other times of the day. While it appears that the analemma is rotating to the west, it is actually the Earth that is rotating to the east. Note carefully the view from the right hand frame. Here, we are standing on the equator, but facing due west. Furthermore, note the position of the analemma around 6:00 p.m. It appears that it’s lying on its side.

The differences between the times of the solstices and rise and set times becomes more exaggerated the closer we are to the equator. In reverse, at either pole, the analemma has no effect on sunrise and sunset times. By downloading and running the SunGraph application, you can see the effect of the analemma on rise and set times almost anywhere on Earth.

	Time Zone Maps

		(688K file size).

		(224K file size).