Measuring the mass of 70,000 aging stars reveals older center, younger outskirts
M. Ness, G. Stinson/MPIA
KISSIMMEE, Fla. — Our galaxy was built from the inside out. That’s the clear conclusion from an unprecedented survey of the ages of tens of thousands of the galaxy’s stars, reported January 8 at a meeting of the American Astronomical Society. “The Milky Way grew up by growing out,” Melissa Ness, an astronomer at the Max Planck Institute for Astronomy in Heidelberg, Germany, said at a news conference.