[In Depth] Hubble uses galactic lens to study universe's first stars
In a just-completed observing program, astronomers fitted the Hubble Space Telescope with the cosmic equivalent of a telephoto lens. Their goal was to scour the oldest and most distant reaches of the cosmos for the small, dim galaxies that probably held most of the first stars. Hubble's vision isn't keen enough, so its handlers aimed it at six massive galaxy clusters—groupings of hundreds or thousands of galaxies—hoping for a boost from a phenomenon, gravitational lensing, originally predicted by Albert Einstein. With their masses bending light from background objects, the thinking went, these clusters would bring fainter galaxies into view. Astronomers are just starting to pour over data from this Frontier Fields program, but early results promised to shed light on the so-called epoch of reionization—the time when the universe was less than a billion years old and something blasted the neutral gas scattered through space after the big bang, stripping...