What does this number measure?
The galaxy that contains the Sun and our planet. The Milky Way is a barred spiral galaxy. We observe it from within, so an external view of the whole galaxy is a reconstruction, not a photograph taken from another system. The Solar System marker is placed in the disc, on an arm, at an indicative position; this diagram is not an astrometric map.
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.
Compare with Barred spiral galaxy NGC 1300 in the explorer →
Source and limitations
Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.
Milky Way: conceptual reconstruction viewed from outside, not a photograph; the arms and disc boundary are approximate.