The Distance to the Andromeda Galaxy
In 1923, Edwin Hubble discovered a Cepheid variable star in the Andromeda
"nebula."
![m31cepbig.gif (27170 bytes)](images/m31cepbig.gif)
The period-luminosity relation shows that
the Andromeda galaxy is 2.5 million light years away.
A primary mission of the Hubble Space Telescope is to discover
very distant Cepheid variable stars.
back | next | index