When Henrietta Leavitt discovered the period-luminosity relationship, she used Cepheid variable stars that were all located in t
he Large Magellanic Cloud (LMC). It was (easier / more difficult ) to compare Cepheids in the LMC rather than those located in the Milky Way Galaxy because they are all ( about the same distance away / located at widely varying distances from Earth ). As a result ( differences in apparent brightness are directly related to differences in intrinsic brightness of these stars / all of these stars have the same Doppler shift / all of these stars have the same proper motion )
Easier, about the same distance away, differences in apparent brightness are directly related to differences in intrinsic brightness of these stars
Explanation:
When Henrietta Leavitt discovered the period-luminosity relationship, she used Cepheid variable stars that were all located in the Large Magellanic Cloud (LMC). It was easier to compare Cepheids in the LMC rather than those located in the Milky Way Galaxy because they are all about the same distance away. As a result differences in apparent brightness are directly related to differences in intrinsic brightness of these stars.
