M31-V1
Classical Cepheid variable · Hubble variable number one
The star that proved other galaxies exist
Perhaps the most important star in the history of cosmology. In 1923 Edwin Hubble watched this faint Cepheid brighten and fade in Andromeda, used its steady rhythm to measure the distance, and proved the spiral was a whole galaxy far beyond the Milky Way. The universe got much bigger that night.
Illustration from its stellar type, not a photograph
2.5 million ly
from Earth
19.2
apparent magnitude
Its light has been travelling 2.5 million years to reach us, so you see M31-V1 as it was 2.5 million years ago.
Source · Templeton et al. 2011, PASP 123, 1374 · View on Wikidata
It lives in
Andromeda Galaxy
Spiral galaxy, 2.5 million ly away.
Other notable stars in Andromeda
Worlds in the same direction on the sky→