Why does Sirius, despite being intrinsically brighter and larger than the Sun, appear only as a point source?

Answer

Its light travels too far before reaching our atmosphere.

Because Sirius is vastly farther away than the Sun (8.6 light-years compared to 1 AU), its light travels too far, preventing it from subtending a measurable angular diameter and causing it to appear as a point source.

Why does Sirius, despite being intrinsically brighter and larger than the Sun, appear only as a point source?

#Videos

Why The Sun is Bigger Than You Think - YouTube

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