In astronomy and celestial navigation, an ephemeris gives the positions of astronomical objects in the sky at a given time. The class Ephemeris implements an ephemeris model based on the research of Jensen et al. [1].

The Ephemeris class takes the current time and the position on the Earth (longitude/latitude/altitude) as input. With this info it calculates the positions of the sun and moon, the moon phase and several transformation matrices which can be used to convert between different celestial coordinate systems. These can be used to orient the stars and Milky Way cube maps correctly.

This class can also compute the direct light and ambient light from the sun and the moon using a physically-based model of the Earth's atmosphere and NASA data of the sun's spectrum.

[1] Jensen et al.: "A Physically-Based Night Sky Model", http://graphics.stanford.edu/~henrik/papers/nightsky/nightsky.pdf