Although his geometry was perfect, Aristarchus' methods of measurement were extremely inaccurate. His basic value for the angle from Sun to Earth to Moon was off by a few degrees (the actual value is 89 degrees, 50 minutes), and the width of the earth's shadow cone at the moon is actually three rather than two moon diameters. Using improved values, we can show that the sun is about 400 times farther from the earth than the moon, and its diameter is approximately 109 times greater than that of earth.