What Is the Period-Luminosity Relation for Cepheid Variables?

💡 The Answer

• Discovered by Henrietta Swan Leavitt in 1908 while studying variable stars in the Magellanic Clouds.
• Brighter Cepheids have longer pulsation periods, a direct and predictable relationship.
• This relation allows astronomers to determine intrinsic brightness from period alone.
• Comparing apparent brightness yields the star's distance, a key cosmic yardstick.