export type Vec3 = [number, number, number];
/** Unit vector on the sphere for an (ecliptic longitude, latitude) pair, in the
 *  ecliptic frame: x toward 0 Aries, z toward the north ecliptic pole. */
export declare function unitVector(lonDeg: number, latDeg: number): Vec3;
/** True great-circle angle (degrees) between two bodies from their ecliptic
 *  longitude and latitude. With both latitudes zero this is the unsigned
 *  longitude difference; latitude pulls the two apart in three dimensions. */
export declare function angularSeparation3d(lonA: number, latA: number, lonB: number, latB: number): number;