1 Million Habitable Planets Could (Theoretically) Orbit a Black Hole. Here's How

[Judi Lynn]

By Charles Q. Choi, Space.com Contributor | June 11, 2018 07:24am ET

A black hole could have 1 million planets orbiting near it that are potentially capable of supporting life as we know it, an astrophysicist suggests.

Since there is life virtually everywhere liquid water exists on Earth, astronomers often judge a world as potentially habitable if it orbits within a zone where liquid water could survive on its surface. Our sun's "habitable zone" hosts just one planet (Earth), but the story could be different for other stars. For example, the TRAPPIST-1 system has three Earth-size planets within its habitable zone.

Sean Raymond, an astrophysicist at the Observatory of Bordeaux in France, researches how planetary systems form and evolve. As part of a column Raymond writes called "Building the Ultimate Solar System," he set out to see how many planets could orbit a black hole. [The Strangest Black Holes in Space]

"I think we can learn from the extremes ... they are basically the boundaries of the box in which we are searching," Raymond told Space.com. "This system is one extreme — the most packed imaginable. It's a fun blend of imagination and science."

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[JayhawkSD]

1. Pretty narrow definition of "life."

"...astronomers often judge a world as potentially habitable if it orbits within a zone where liquid water could survive on its surface."

That assumes that "life" is not only carbon based, but is water based. Life could be silicon based, or based on any other molecule capable of forming chemical bonds.