This Hubble image of a crowded star field in the disk of the Andromeda galaxy. Credit: Ben Williams, Julianne Dalcanton and the PHAT Collaboration
This Hubble image of a crowded star field in the disk of the Andromeda galaxy shows that stars of different ages can be distinguished from one another on the basis of temperature (as indicated by color) and brightness. Credit Ben Williams, Julianne Dalcanton and the PHAT Collaboration