Astronomers have used careful measurements of star brightness originally gathered for spotting planets for a new purpose: guessing the age of our galaxy.

After tracking “star-quakes,” they believe a more accurate estimate is that the Milky Way is 10 billion years old.

When NASA’s Kepler satellite was scouring the skies for exoplanets, it found them by carefully watching a star’s brightness for the telltale dimming caused by a planet passing in front of it. While Kepler’s mission is complete, the data it collected keeps on giving: a team of scientists led by researchers at the Sydney-based ARC Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO-3-D) have used the data to estimate star ages, and thus the galaxy’s birthdate, too.

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