Dear Fellow Diallists, Shadow watching Eratosthenes is well known for his calculations of the Earth's circumference. But amongst many other things, he also calculated the angle of the home planet's ecliptic as 23 51' 19''. Ptolemy's results were slightly higher. Vitruv estimated 360/15=24 degrees. All are now considered to have overestimated the angle for that period, if only marginally. But how did they do it? What method was actually involved in calculating the angle of the inclination of the Earth's axis, relative to the plane of its orbit? Can anybody help?
Yours curiously Heiner Thiessen 51N 1W -
