Distance indicator · Secondary rung
Tully–Fisher Relation
An empirical relation for spiral galaxies between how fast they rotate and how luminous they are — the faster the rotation, the brighter the galaxy. Measuring the rotation (from the width of the 21-cm line) then gives the luminosity, and comparing with the apparent brightness gives the distance.
Methods, objects & facilities
Knowledge connections
- Associated withThe Cosmic Distance Ladder
- Associated withSpiral Galaxy
- Associated withGalaxy Rotation Curves
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.