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Orthographic projection is way of figuring out where the Sun or Moon will rise or set on any day of the year, at any latitude (between the Polar Circles), with any angle of elevation to the horizon. We've arranged these exercises in a specific order where each one builds from previous examples, but of course you can go to any section.

There are three reasons why you may want to know how to do orthographic projection.

  1. To check suspected astronomical alignments at ancient sites.
  2. In new sacred spaces, to discover astronomical alignments to significant astronomical rises and sets to the Solstices, Equinoxes and the Cross-Quarter Days.
  3. To learn to see our planet in a different way.

These are rather big files, and you may prefer to work through this material off-line by downloading them:

In Section 1, we show you how to calculate Solstices & Equinoxes.

In Section 2, we will show you how to calculate the Sunrises and Sunsets at the Celtic Cross-Quarter Days of:

In Section 3, we work with an elevated horizon.

In Section 4, we show you how to determine the major and minor standstills of the Moon.


We also have a cgi script running on this site called Sunfinder where you can enter your latitude, azimuth, angle of elevation to the horizon, and it can tell you what day of the year the Sun will rise at that particular point on the horizon. ButI would encourage you to do Orthographic Projection first. It wil give you a real feel for how, through the year, the Sun and Moon move through the heavens at your latitude.

If you do not know your latitude, Google Earth is an easy way to find it. You can have a free download of this useful program at < http://earth.google.com/

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