A toddler can seem to have boundless energy as they scamper around the house and playground. Most adults, on the other hand, set a more measured pace going about their day.

Much like humans, stars gradually lose steam over time. They are born spinning rapidly, but slow down over billions of years. (Our 4.5-billion-year-old Sun spins about once per month.)

After about one billion years, stars of the same mass and age will spin at the same rate. Therefore, if you know a star’s mass and rotation rate, you potentially can estimate its age. NASA’s Nancy Grace Roman Space Telescope is poised to measure the spin rates, and calculate the ages, of hundreds of thousands of stars after it launches by May 2027.