How could you determine the diameter of the sun? What method do you use?

1 Answer
Mar 19, 2016

From the angular spacing #alpha# of the solar disc, using diameter = 2 #tan(alpha/2)# AU = 2 X 149597870 X tan#(alpha/2)# km.

Explanation:

The best location and time for precision is from a ship in the sea near New Papua Guinea at noon, on vernal/autumnal equinox day
Here the latitude is near 0, the Sun will be right-overhead and the error will be minimum.

Of course, there are similar locations at latitude 23.4 deg S and 23.4 deg N, on winter and Summer Solstices, for right-overhead Sun.

The precision will be better, if the Sun's actual distance on the day of observation is applied, instead of AU. AU is the average distance only. For equinox, AU is fairly a good approximation to the actual distance.

Some corresponding sample values of #alpha# and diameter are 0.5313 deg and 1387221 km.