With Kalgash 4, Raymond imagined an Earth-like planet orbiting a black hole in between two rings of sun-like stars, with an inner ring of eight sun-like stars 2 AU wide, and an outer ring of eight sun-like stars 20 AU wide. (Image credit: Sean Raymond/Black hole visualization courtesy of Paramount/Universal) An Earth-like planet orbiting one of these 12 stars could also experience permanent daylight.Īstrophysicist Sean Raymond's Kalgash 4 concept would place a planet in permanent daylight using a system with a black hole at its center and the planet orbiting between two rings of sun-like stars. The planet is tidally locked, meaning one side constantly faces its star, and its backside is constantly lit by the ring of sun-like stars.Īnother scenario, dubbed Kalgash 3, imagined a ring of a dozen sun-like stars 40 AU wide orbiting a black hole a few thousand solar masses in size. Halfway between this ring and the black hole is a red dwarf star half the sun's mass, around which an Earth-like planet orbits at just 0.2 AU. One version of Kalgash that Raymond modeled, dubbed Kalgash 2, had a black hole a few thousand times the sun's mass with eight sun-like stars in a ring around it 40 astronomical units (AU) wide, an AU being the average distance between Earth and the sun, about 93 million miles (150 million kilometers).

Raymond calculated that a ring of sun-like stars could be stable if there are at least seven stars in the ring, they all have the same mass, they are all evenly spaced along the same orbit, and they orbit something a lot more massive - in the case of a ring of seven sun-like stars, a black hole at least 1,000 times the sun's mass. That requires at least one ring of stars. Raymond then sought out to illuminate the side of a planet facing away from its central star.

The Kalgash 3 concept by astrophysicist Sean Raymond would place an alien planet in an orbit like that of Earth around a sun-like star, which is part of a ring of 20 stars in all, that orbits a central black hole.

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