Fingerprinting the Very First Stars

This artist concept shows one of the universe’s first stars. The massive blue star is embedded within filaments of gas and dust, while the cosmic microwave background (CMB) is shown on the outer edges. Researchers recently inferred the existence of these massive blue stars by measuring the dimming of the CMB. (Credit: N. R. Fuller/National Science Foundation) When solving a crime, detectives don’t always have access to footage or photographs of their suspect. Instead, the detectives have to painstakingly search for small, easily overlooked clues — such as fingerprints. Like detectives, astronomers don’t always have the option of simply examining an image when they want to solve a mystery. Instead, astronomers usually must meticulously piece together tiny bits of evidence, often by scouring the heavens to hunt for clues. And one of the biggest cosmic cold cases that astronomers have been attempting to solve for years is: When exactly did ...