Calculates the distance between a body and the Sun at a given time.
Given a date and time, this function calculates the distance between
the center of body and the center of the Sun.
For the planets Mercury through Neptune, this function is significantly
more efficient than calling HelioVector followed by taking the length
of the resulting vector.
Calculates the distance between a body and the Sun at a given time.
Given a date and time, this function calculates the distance between the center of
bodyand the center of the Sun. For the planets Mercury through Neptune, this function is significantly more efficient than calling HelioVector followed by taking the length of the resulting vector.