Giant Lasers Bring Distant Twinkling Stars Into Sharp Focus

The twinkling of a starry night sky is romantic, sure. But for astronomer Dominika Wylezalek, “it’s a nightmare.” That’s because Wylezalek studies galaxies billions of light-years away, and all that finicky glimmering—she’d call it “turbulence”—gets in the way. So she and her colleagues at the European Southern Observatory fire up this Star Wars–worthy laser cannon in northern Chile to measure distortion in the atmosphere and improve the astronomical image.

The device shoots four 22-watt laser beams—each nearly a foot in diameter and 4,000 times as powerful as a laser pointer—into the sky, where they radiate at a wavelength of 590 nanometers, exciting sodium atoms in the upper atmosphere. When the atoms get whipped into a frenzy, they emit photons that shine like stars. Those artificial stars form reference points for the telescope, helping its internal mirror correct for pesky twinkling. It’s like the autofocus on a camera. The result: vastly sharper photos. “We’re trying to push the telescope to not see any distortion from the atmosphere at all,” Wylezalek says. For the past two years, this laser blaster has been shedding new light on the darkest reaches of space. In 2019 it will be used to study super­-massive black holes in far-off galaxies and dense star clusters within the Milky Way, revealing formerly hazy secrets of stellar evolution in hi-def.