Cosmology
Terearth is a small, hemi-spherical planet that possesses rather unusual cosmological features.
Size
Terearth, as a planet is unusually small. From poles to the equator, Terearth is about 2000 miles (3200 km). For those of you who have difficulty imagining how small that is, a comparison image is to the right.
Position in the Universe
Most learned scientists agree that Terearth is at (or very close to) the centre of it's local planetary system, if not the centre of the Universe itself. The sun and moons orbit Terearth on a regular and predictable pattern. There are arguments that the stars themselves also slowly orbit Terearth although those who believe the stars to have special religious significance dispute these findings.
Recently there appears to be some evidence that there are other planets orbiting Terearth but as these can only be viewed with sophisticated optics, it is assumed they are either very small or very far away. In fact there is much suspicion that they are not planets at all but that they are in fact additional moons of Terearth.
Physical data
The world of Terearth is, effectively, a smooth hemi-sphere on one side and jagged rocks on the other. The "smooth" side is the habitable side - the side with the land and sea on. The non-spherical half of the planet is said to resemble a vast mountain range, with peak hundreds of miles high. In the centre of this region is the immense chain than links Terearth to the Celestial Anchor. This is a highly dense artefact which holds the planet firmly in its place in the cosmos.
Satellites
Terearth has two natural satellites named Arko and Bezla.
Bezla is a pale green, spherical, ringed moon, which resembles a small Saturn. From Terearth, Bezla appears to be the same relative size as our own moon. However, as Terearth itself is only slightly larger than Earth's moon, this would presumably make Bezla either very small or considerably further away. Arko is the larger of the two (about 30% larger in the night sky than Bezla)and looks like an irregular lump of rock.
It is the phases and position of Arko that regulate the Imperial calendar. Arko also appears to have an effect on the tides, although there is debate amongst Terearth's scientists as to how strong this interaction is.
Oddly it is the phases of Bezla that affect those inflicted with the curse of lycanthropy. Bezla is also factored into most calculations required for astrology and of the Dark Arts.
Image from http://www.solarviews.com
Terearth's Sun
Like our Earth, Terearth has a single yellow star. It is the movement of this star that determines the years on Terearth, which are of a similar length to our own years.
Gravity
Despite Terearth having approximately the same dimensions as Mercury, the planet's gravitational pull is actually very similar to that of our own planet. The acceleration due to gravity, g, works out at exactly 9.5m/s (or 97% of ours). This relatively high gravity for such a small celestial body is still largely unexplained but there are a number of theories;
1) Terearth's gravity could come not from it's own mass but, in part, from Terearth's own orbit about the Celestial Anchor, and the weak gravitational effect of it's two moons.
2) Terearth may have a core which is not iron (as with Earth) but some other element, with a much higher density.
3) Terearth's gravity may be artificially higher than expected through some unexplained artefact or magic.
Regardless of the actual reason, all players need to know about is that, despite it's size, Terearth's planetary physics roughly mimic that of our own world.
Constants
As far as the inhabitants of Terearth are concerned, light travels very, very fast (much faster than, say, an arrow). As far as players need to know, light on Terearth travels at the same speed as on Earth. However, unlike in our reality, the speed of light is not entirely constant and can be altered by very powerful magics.
Magnetism
Terearth's "magnetic pole", as with the magnetic pole of Earth, "flips" every million or so years. Terearth's magnetic north pole headed south a few hundred thousand years and so, technically, a compass from Earth would point towards the south if used on Terearth.
The inhabitants of Terearth are, largely, unaware of this though. Those that have magnetic compasses just have the other end painted red.
Note that, unlike Earth, Terearth suffers none of the magnetic declination that is observed on Earth. On Terearth, magnetic South and geographic south are exactly the same thing. For more information on "magnetic declination" on Earth see http://en.wikipedia.org/wiki/Magnetic_north
