sun_direction_eci

Defined in: ephemeris.rs:70

fn sun_direction_eci(epoch: &Epoch) -> [Vec3<frame::Gcrs>](../../structs/vec3/)

Approximate sun direction (unit vector) in ECI (J2000) frame.

Uses a low-precision analytical model based on mean orbital elements. Accuracy is ~1 arcminute, sufficient for visualization purposes.

Reference: Meeus, “Astronomical Algorithms”, Chapter 25.