Function skyDistanceDegrees( ra1, dec1, ra2, dec2 )

Description:
Calculates the separation (distance around a great circle) of two points on the sky in degrees.
Parameters:
ra1 (floating point)
right ascension of point 1 in degrees
dec1 (floating point)
declination of point 1 in degrees
ra2 (floating point)
right ascension of point 2 in degrees
dec2 (floating point)
declination of point 2 in degrees
Return Value (floating point):
angular distance between point 1 and point 2 in degrees
Signature:
double skyDistanceDegrees(double, double, double, double)