Convert from ecliptical to equatorial coordinates, using equations 8.3 and 8.4 of reference 1, or, equivalently, equations 12.3 and 12.4 of reference 2.

eclipticalToEquatorial(lambda, beta, epsilon)



longitude, in degrees, or a data frame containing lambda, beta, and epsilon, in which case the next to arguments are ignored.


geocentric latitude, in degrees


obliquity of the ecliptic, in degrees


A data frame containing columns rightAscension and declination both in degrees.


The code is based on reference 1; see moonAngle() for comments on the differences in formulae found in reference 2. Indeed, reference 2 is only cited here in case readers want to check the ideas of the formulae; DK has found that reference 2 is available to him via his university library inter-library loan system, whereas he owns a copy of reference 1.


  1. Meeus, Jean, 1982. Astronomical formulae for Calculators. Willmann-Bell. Richmond VA, USA. 201 pages.

  2. Meeus, Jean, 1991. Astronomical algorithms. Willmann-Bell, Richmond VA, USA. 429 pages.

See also