Declination, Parallels and Contraparallels
The relationship two bodies can have across the plane rather than along it — and why the frame you select decides which measurement it is matched in.
The relationship two bodies can have across the plane rather than along it — and why the frame you select decides which measurement it is matched in.
Right ascension and declination, measured from the celestial equator — the astronomer's frame, and the one the sky's daily turn makes natural.