What causes the Sun to appear as a distinct disc while other stars appear as point sources of light?

Answer

The Sun's proximity.

The Sun's close distance results in a large angular diameter (about 32 arcminutes), allowing it to be resolved as a sphere by the naked eye. Stars millions of times farther away, even if larger, subtend an angle too small to resolve.

What causes the Sun to appear as a distinct disc while other stars appear as point sources of light?
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