@type t() :: %Angelus.Ephemeris.BodyPosition{
  body: atom(),
  distance_au: float() | nil,
  latitude: float() | nil,
  light_time_seconds: float() | nil,
  longitude: float() | nil,
  metadata: map() | nil,
  position_km: {float(), float(), float()} | nil,
  spice_id: non_neg_integer() | nil,
  spice_target: String.t() | nil,
  target_kind: :body_center | :lunar_node | :lunar_apogee | :minor_planet | nil,
  velocity_km_s: {float(), float(), float()} | nil
}

Geocentric ecliptic position of a celestial body.

Fields:

• :body — the body atom (e.g. :sun, :moon).
• :spice_target — SPICE target name string (e.g. "SUN").
• :spice_id — SPICE integer ID for the target.
• :target_kind — one of :body_center, :lunar_node, :lunar_apogee, or :minor_planet.
• :position_km — {x, y, z} position vector in km (ECLIPJ2000 frame).
• :velocity_km_s — {vx, vy, vz} velocity vector in km/s.
• :light_time_seconds — one-way light travel time from target to observer.
• :longitude — geocentric ecliptic longitude in degrees [0, 360).
• :latitude — geocentric ecliptic latitude in degrees.
• :distance_au — distance from Earth to the body in astronomical units.
• :metadata — internal metadata map (engine, kernels, SPICE settings, etc.).