To help me you will need tho know Excel VBA very well. Earth has an elliptical orbit around the sun. JPL's website has the data to calculate this orbit: http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt In the spreadsheet the parameters are calculated from widely used equations and some of my making. The major discrepencies are in how to calculate the distance between the Earth and the Sun,r. By my calculations: r<1AU and a minimum @True Anomaly=0 r>1AU and a maximum @True Anomaly=180 This is not the case when directly calculated from the table(In Green). My calculations of what they should be are in yellow. Any suggestions would be deeply appreciated!