HOW BIG
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Galaxies

Andromeda Galaxy: size, dimension and comparison

The adopted reference is about 219,860 light-years.

approximate disc diameter

A light-year is a distance: how far light travels in one year. It is used for distances between stars.

The large spiral galaxy neighbouring the Milky Way.

Explore at this scale
Andromeda Galaxy, interpreted illustration
Interpreted illustration · dimension stated in the fact sheet.

What does this number measure?

The large spiral galaxy neighbouring the Milky Way. Andromeda, or M31, belongs to the Local Group. Its stellar disc fades gradually without a sharp edge; the adopted diameter depends on the depth of the observations.

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 Pinwheel Galaxy · M101 in the explorer →

Source and limitations

Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.

Andromeda: an interpretation of the inclined disc and dust; approximate colours and luminous boundaries.

Illustration sources

How Big — generated illustration; NASA/ESA documentation.

Source coverage: Visual interpretation; colours and texture do not constitute an observation. Only the designated extent follows the catalogue's reference value.