The spherical coordinates in this system are the heliocentric distance \(r\), the ecliptic longitude \(λ\), and the ecliptic latitude \(β\), such that \(X = r \cos β \cos λ\), \(Y = r \cos β \sin λ\) ...The spherical coordinates in this system are the heliocentric distance \(r\), the ecliptic longitude \(λ\), and the ecliptic latitude \(β\), such that \(X = r \cos β \cos λ\), \(Y = r \cos β \sin λ\) and \(Z = r \sin β\). Heliocentric equatorial coordinates. \(\odot ξηζ\) with the \(\odot ξ\) axis directed towards the First Point of Aries and therefore coincident with the \(\odot X\) axis . The angle between the \(\odot Z\) axis and the \(\odot ζ\) axis is \(ε\), the obliquity of the ecliptic.
