This is one of a series of guides to the Shadeward Universe. You can read the others here.
With a relative lack of technology available to the inhabitants of Esurio, the means of navigating long distances across the planet has been lost to most. There are no compasses or GPS systems available. However it is still possible to determine your location to a high degree of accuracy. The map that Meru finds in the first book is based upon the design below and gives clues as to how it operates. With this knowledge it is possible to navigate successfully.
Whilst Esurio does have a rotational pole like the Earth, it is not useful as the basis of navigation as the rotational period matches the orbital period (tidally locked). All measurements are taken from the ‘substellar pole’, (the point on Esurio where the star is directly overhead). Lines of longitude spread out in circles from this point measured in traditional degrees. Measuring your latitude is thus done in the same fashion as it is on Earth, calculating the angle of the star above the horizon. However, it is reversed numerically. Overhead = 0, On the horizon is 90.
As it was on Earth prior to the invention of clocks, longitude is much more problematic to determine – most cultures are unable to do it. There are no clocks on Esurio, and whilst the sand-timers used to regulate activity can measure elapsed time, this method is not accurate enough. Fortunately Esurio benefits from an additional phenomena that Earth does not, the regular transit of a large planet in an interior orbit. Mayura is a gas-giant (a hot jupiter) in an orbit closer to Lacaille 9352 than Esurio. From the perspective of Esurio, it cross the face of the star on a regular (roughly monthly in Earth terms) basis. This ‘Pass’ is the basis of all time-keeping on Esurio.
As Esurio orbits in the same plan as Mayura, it possible to calculate longitude based on the observed angle of the transit. if the transit is ‘flat’ you are observing from the ‘centre’ line of the planet, the meridian. If the transit is measured at an angle, you are away from that centre line by the observed amount.
With the star constantly over the substellar pole, the areas immediately below that point receive immense amounts of infra-red energy (heat). As latitude increases, the star is lower in the sky until is lost from view. With the star motionless in the sky some areas are too hot and others too cold, with a relatively narrow temperate area between them where conditions are suitable for life. You’ll note on the map above that most cities are between 50 and 70 degrees of latitude. Outside of this, Nireus (Lat 74) is particularly cold (on the borders of the Frozen Wastes) and Airea (Lat 43) is extremely hot.
Given its nature, Esurio does not have North, South, East or West. Directions are either directly away from the star (Shadeward), or towards it (Sunwards). You can also move with the sun on your right (Sunright) or with the sun on your left (Shaderight). Both of these latter directions will ultimately describe a circle of longitude.
Amaris , in the land of Amar is Latitude 61 degrees Shadeward, Longitude 38 degrees Sunright.
Daine, in the land of Drayden, is Latitude 56 degrees Shadeward, Longitude 17 degrees Shaderight.
The Frozen wastes typically start at Latitude 70 degrees Shadeward.