# How do you measure the diameter of the sun?

##### 1 Answer

#### Explanation:

This is an approximation, with negligible error.

The formula is perfect for right-overhead-noon observation-.

Best location is equator-equinox-noon-location, around March 21.

Of course, there is limitation, in the precision for measurement of the angular spacing, of about 0.001".

The observer O's distance from the center S of the Sun is

The formula is from a right angled

OP a tangent to the solar disc.

SP is a radius of the Sun.

Using d = 1 AU = 149597870 km, r = 6378 km,

There are slight variations in the reported diameter, in different sources.

I have given only 4-significant digits (sd) approximation. If more sd are needed,