The AU is wrong because it's derived by studying the position of the sun from two far off places on earth and assuming that it is a globe by accounting for its supposed curvature.

Each astronomer throughout history has measured distance of the Earth and Sun by using triangulation between two distant points on Earth, observing the Sun and measuring the angle of the sun in the sky in relation to the sea-level of the Earth. An astronomer could either triangulate the Sun's distance from the Earth to 93 million miles

**or** 3,000 miles. It entirely depends on whether the earth appears as flat or round in the author's triangulation equations. Different angles mean different things on an RE and an FE.

For example,

this link shows us how modern Round Earth science calculated the distance between the Earth and Sun using the transit of Venus. You will immediately notice that the equations are highly dependent on the assumption of a Round Earth.

If we take those same triangulation equations and use them under the assumption of a Flat Earth and do away with the compensation for the curvature of the Earth, assuming a flat surface, the final equation for the distance between the Earth and Sun becomes

rT = (PT / PV)2/3 (1 - eT cos ET) / (1 - eV cos Ev)

When we plug in the numbers from that link, the figure 'rT', the distance between the Earth and Sun, is equated out to an approximation close to 3,000 miles.

Finally, the angular size of the sun is 0.5°. Using this fact with a distance to the sun of 3000 miles, gives the sun's diameter: 32 miles.