# How do you find the diameter of the sun?

##### 1 Answer

A good approximation to the diameter can be computed from the angular spacing

Vernal Equinox Sun (about Mar 21, near New Papua Guinea).

#### Explanation:

The formula is

Diameter of the solar disc =

where

1 AU =149597871 km and r = equatorial radius of the Earth = 6378 km.

For these values, diameter = 2.992 E+08 tan (

Sample data: Against

The line of centers of the Sun and the Earth passes through the observer at the chosen instant and location.

The vernal equinox right-overhead-Sun noon occurs in the proximity of New Papua Guinea island on the equator, by Mar 21.

For any other instant and latitude,this formula indeed gives an approximation that is not so precise.

This approximation can be further improved by considering the fact that what is observed as the diameter of the glowing solar disc falls a little short of the the actual diameter of the Sun.

The answer can carry more significant digits (sd), if the radius of the Earth and the angular spacing are known with higher precision in sd.