Tag Archives: Nightfall

No habitable planets for at least one globular cluster

Calculations by astronomers now suggest that the crowded nature of the giant globular cluster Omega Centauri will probably make it impossible for habitable planets to exist there.

In the hunt for habitable exoplanets, Omega Centauri, the largest globular cluster in the Milky Way, seemed like a good place to look. Comprising an estimated 10 million stars, the cluster is nearly 16,000 light years from Earth, making it visible to the naked eye and a relatively close target for observations by the Hubble Space Telescope.

…[T]he cozy nature of stars in Omega Centauri forced the researchers to conclude that [habitable] planetary systems, however compact, cannot exist in the cluster’s core. While our own sun is a comfortable 4.22 light years from its nearest neighbor, the average distance between stars in Omega Centauri’s core is 0.16 light years, meaning they would encounter neighboring stars about once every 1 million years.

“The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets,” Deveny said. “Looking at clusters with similar or higher encounter rates to Omega Centauri’s could lead to the same conclusion. So, studying globular clusters with lower encounter rates might lead to a higher probability of finding stable habitable planets.”

Science thus concludes that Isaac Asimov’s classic science fiction short story, Nightfall, is unlikely.