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