orrery was typically a centerpiece of the eighteenth century London
coffeehouse and its lectures.
Lecturers would use the orrery to demonstrate the motions of
planets around the sun, and moons around the planet, explaining such
phenomena ranging from comets, eclipses and the waxing and waning of the
moon to the seasons and day and night.
Through the perfect motions of the planets, the omnipresence of
God was oft implied.
In the eighteenth century, the outer planets Uranus, Neptune and Pluto were not yet known to exist (as well as a lot of the minor moons of the gas giants and the two moons of Mars).
Thus, the virtual orreries herein (as well as the real orreries) only feature six planets and some of their major moons. The order of the planets featured are Mercury, Venus, Earth, Mars, Jupiter and Saturn, in that order from innermost to outermost.