Revised November 2005: added data relating to seasons, equinoxes and solstices.

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The point of view
Imagine you are in a spacecraft in the same solar orbit as earth, you are
looking towards Earth and following some way behind.

My goal was to link a calendar to the lunar cycle with reasonable accuracy
over a useful time span. I believe it's now accurate to within a day over the
period covered by the calendar.

Limitations
The calendar is constrained to work in the range of dates between
January 1st 1800 and December 31st 2299.

Scale is not exact, and the path of the moon's orbit is an approximation.

In the 3D model, the moon orbits the Earth around an equatorial plane.
In reality, the moon's orbit is at an angle to this plane.

If you observe the moon at different times during the course of a day,
the tilt of its shadow changes. In this model that doesn't happen.
To do so, would require the user identifying where they are on Earth.
This is something I'd like to implement in a future version.

The seasons
The model takes into account the tilt of the Earth's axis as it travels on its
orbit around the sun. While the tilt remains at about 23.5 degrees, the
apparent tilt from our perspective in our space craft changes throughout
the year. So for example around December 22, we observe the South polar
region is tilted towards the sun and the North polar region tilted away.
Around June 21, the opposite situation occurs and at the times of the
equinoxes, one of the poles is tilted towards our viewing point,
the other tilted away.

Feedback can be sent to david@pixelpump.co.nz

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