Anuj Gautam

Imagine a person in an old photograph standing in a crowd while spinning — guessing their age would be nearly impossible. That's roughly how astronomers determine the ages and masses of distant stars, and they often get it wrong. For stars slightly heavier than the Sun (from 1.4 to 2.5 solar masses), standard methods like chemical-composition 'clocks' work poorly.

A young star cluster resembles an orchestra before a concert: each instrument tunes up in its own way, and the overall hum seems like chaos. But if you listen closely, you can pick out individual notes.