Before fulfilling its audacious dream of interstellar flight, Breakthrough Starshot—the private effort funded by billionaire Yuri Milner to conduct high-speed robotic voyages to the stars within a generation—must first find a destination.

The project’s primary target is the triple star system Alpha Centauri, our nearest interstellar neighbor at just over four light-years away. Of its three stars, only the red dwarf Proxima Centauri is known to have a planet, an Earth-mass world in a star-hugging orbit where liquid water—and therefore life as we know it—could exist. Astronomers already have plans to closely study this planet, but may find it unwelcoming due to its bombardment with intense flares from its nearby host star. Many believe the system’s larger, brighter and more sunlike stars, the binary pair Alpha Centauri A and B, offer better prospects for life-friendly worlds, even though all previous planet hunts there have come up empty-handed. Thoroughly examining these two stars requires expensive new instruments and many nights on the world’s best, most in-demand telescopes—boons just as elusive as Alpha Centauri’s planets. For years, this relative lack of resources has rendered any worlds around Alpha Centauri A or B effectively invisible to us, lost in the overpowering glare of those stars.

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