How Do Cepheid Variables Help Measure the Universe?

💡 The Answer

• Cepheid variables pulse regularly with a period directly tied to their intrinsic brightness.
• Astronomers use this period-luminosity relation to calculate distances to faraway galaxies.
• The Hubble Space Telescope observed Cepheids in galaxies up to 100 million light-years away.
• They were key to discovering that the universe is expanding, not static.
• Cepheids serve as the first rung of the cosmic distance ladder for deeper measurements.