How do you measure the diameter of the sun?

Question

Olivia Aldridge · Accepted Answer

#angle# spacing of Sun (S) disc = #theta#. Radius of Earth (E) = r. ES = d. . Answer: #2(d-r)sin(theta/2)# = 1.395 E+06 km, nearly..

This is an approximate value with very little error. The formula works flawlessly for observations made at noon on the right-overhead. The best location is around March 21, at the equator, equinox, and noon. Naturally, there is a 0.001" precision limit on the measurement of the angular spacing. The observer O's distance from the center S of the Sun is #d-r#. The formula is from a right angled #triangle#OSP right angled at P. OP a tangent to the solar disc. SP is a radius of the Sun. Using d = 1 AU = 149597870 km, r = 6378 km, #theta# = 0.5344 deg, the diameter is 1395 thousand km, nearly. There exist minor discrepancies in the diameter reported across various sources. I have given only 4-significant digits (sd) approximation. If more sd are needed, #theta# and r should carry more correct sd.

Owen Atkinson · Answer

undefined The diameter of the sun is measured using methods like solar astrometry, solar interferometry, and helioseismology. Astrometry involves observing the sun from different locations on Earth. Interferometry combines signals from multiple telescopes. Helioseismology studies solar oscillations to infer the sun's structure.