Star clusters could host long-lived technological civilisations
If habitable planets can form inside globular clusters, they would make nice homes for advanced civilisations that talk to each other and travel between the stars.
Globular clusters are dense clumps of stars, with about a million suns packed into a sphere some 100 light years across. They formed early in the Milky Way’s history, around 10 billion years ago. Previously, astronomers had dismissed the possibility that they could host inhabited planets, because their old stars lack planet-building heavy elements and the close proximity of the neighbours could destabilise the orbits of any planets that did form.
But according to a new computer model, such clusters possess a “sweet spot” where small stars can hang on to planets in their habitable zones, where temperatures are right for liquid water and perhaps life. These stars are so close together that hypothetical civilisations wouldn’t have to go as far to travel between the stars as humans would have to.