ONE OF astronomy’s biggest changes of perspective in recent years has been the realisation that planets are abundant in the cosmos. But not everywhere. Collections of stars called globular clusters seem bereft of them.
Globular clusters are roughly spherical collections of hundreds of thousands of stars. These, in turn, are among the oldest stellar inhabitants of galaxies. But though the Milky Way, the Earth’s home galaxy, has more than 150 globular clusters, so far only a single planet has been spotted in one: Messier 4 (see picture).
Nothing daunted, Rosanne Di Stefano of the Harvard-Smithsonian Centre for Astrophysics and Alak Ray of the Tata Institute of Fundamental Research, in India, told the 2016 meeting of the American Astronomical Society why they think globular clusters are a good place to go hunting for advanced civilisations.
First, the clusters’ very age means that life will have had the best chance of coming into existence and then climbing the ladder of complexity to the point where it can travel from star to star. Second, that age also means clusters have stopped being disrupted by life-destroying...Continue reading
Source: Science and technology http://ift.tt/1OQvs9L
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