What does this number measure?
The brightest star in the night sky as seen from Earth. Sirius A belongs to a binary system with the white dwarf Sirius B. Its high apparent brightness depends both on its own light output and on its relative proximity.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.
Sirius A: interpreted photospheric disc; illustrative colour and surface details.