This describes the system for modelling astronomical/astrological bodies
in a way that can be represented in the client.

Positions of bodies are represented on the inside of a sphere which is
an easy naive approach which does work for most cases. Two values are
used to represent the initial position of the bodies in the same way as
latitude and longitude are used to represent terrestrial position.

Various types of body rotate within the scope of this sphere, currently
with a fixed period. Assumptions are made on the reference for this
period based on the type of astronomical body. Suns are assumed to
have a period based on one year, moons are based on one month. The entire
sphere is modelled as rotating around the world with a period of one
day. The length of these time periods is defined by the WorldTime class
which is fully customisable.

HOW DO WE DEAL WITH THE FACT THAT DAYS DON'T REALLY LINE UP?
The number of days in a year is 1 - (number of rotations of world in year),
because of the nature of the rotation round the sun.

HOW DO WE DEAL WITH MULTIPLE MOONS HAVING DIFFERENT PERIODS? MOONS THAT DON'T
FIT INTO A YEAR MAKE THINGS TRICKY.
The days per year should be defined as rotation of world round system
centre point, and the months per year must be defined in terms of
a nominated primary Moon.

The earth's solar system has anticlockwise rotation, by convention. If it
is viewed is being the other way up
