That's What Ya Call A Four-Star Planet

Astronomers report the discovery of only the second quadruple-star system known to host at least one planet. But they suspect there are a lot more such systems out there. Lee Billings reports. March 19, 2015 | |

In his 1941 short story “Nightfall,” describes a planet called Lagash that resides in a . Constantly illuminated from all sides by its, count ‘em, six suns, Lagash experiences dark skies for just a few hours once every 2,000 years. In the story, the rare celestial alignment occurs and darkness descends for the first time in living memory. At which point the inhabitants of Lagash go berserk and burn their cities.“Nightfall” was sci-fi, but we now know the kinds of multi-star planetary systems it describes are real, and more common than once thought. For example, astronomers recently realized that a planet-hosting star system has four suns, the second of its kind ever found. The finding is in the . [Lewis C. Roberts, Jr. et al, ]Our galaxy contains hundreds of billions of stars, and astronomers suspect planets accompany almost all of them. This latest work implies that about four percent of Sun-like stars may exist in quadruple systems. That’s a lot of potential Lagashes.The system just found, called 30 Ari, is 136 light-years from Earth, in the constellation Aries. We had known of three stars there, as well as a planet ten times bigger than Jupiter. The fourth star is the new discovery.The system is arranged as two binary pairs that orbit each other at a distance more than a thousand times that between the Earth and our Sun. The known planet orbits one star in one pair. Its sky would contain two suns, and the more distant binary pair would appear as two very bright stars, visible even during daylight.If the planet and all four of 30 Ari’s stars are co-planar, night could come to one hemisphere of the world only once every several millennia, when all four stars briefly align on the opposite side. But put aside any Asimovian fears. Life as we know it could not exist on the gas-giant planet, and its nearby suns would incinerate any cities all on their own. No frenzied inhabitants required.—Lee Billings