wgs84 top-level constant

Earth const wgs84

Implementation

const wgs84 = Earth._(
  radius: 6378.137,
  mu: 398600.5,
  j2: 0.00108262998905,
  j3: -0.00000253215306,
  j4: -0.00000161098761,
  flattening: 0.0033528106718309306,
);