By detecting the radioactive remains of material hurled into space by dying stars, astronomers have estimated that, on average, our galaxy churns out seven new stars each year.
The researchers used the European Space Agency's INTEGRAL spacecraft to record gamma-ray light, which is high-energy radiation undetectable from Earth's surface. They collected the particular wavelength that arises from the radioactive decay of aluminum-26. The distribution of this aluminum isotope traces the location of dead massive stars in the Milky Way. These stellar heavyweights forge nearly all the galaxy's aluminum, which they expel when they die in explosions known as supernovas.