Today’s ‘Galaxy’ Insight –“A Globular Cluster Might be the 1st Place Advanced Alien Life is Detected”



“We call it the ‘globular cluster opportunity,’” says Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics (CfA). “A globular cluster might be the first place in which intelligent life is identified in our galaxy. Sending a broadcast between the stars wouldn’t take any longer than a letter from the U.S. to Europe in the 18th century. “Interstellar travel would take less time too. The Voyager probes are 100 billion miles from Earth, or one-tenth as far as it would take to reach the closest star if we lived in a globular cluster. That means sending an interstellar probe is something a civilization at our technological level could do in a globular cluster,” she adds.


The Milky Way hosts about 150 globular clusters, most of them orbiting in the galactic outskirts. They formed about 10 billion years ago on average. As a result, their stars contain fewer of the heavy elements needed to construct planets, since those elements (like iron and silicon) must be created in earlier generations of stars. Some scientists have argued that this makes globular cluster stars less likely to host planets. In fact, only one planet has been found in a globular cluster to date.  The ESO image above shows 47 Tucanae – the second most luminous globular cluster in the Milky Way, after Omega Centauri.



However, Di Stefano and her colleague Alak Ray of the Tata Institute of Fundamental Research in Mumbai, India, argue that this view is too pessimistic. Exoplanets have been found around stars only one-tenth as metal-rich as our sun. And while Jupiter-sized planets are found preferentially around stars containing higher levels of heavy elements, research finds that smaller, Earth-sized planets show no such preference.

“It’s premature to say there are no planets in globular clusters,” states Ray.

Another concern is that a globular cluster’s crowded environment would threaten any planets that do form. A neighboring star could wander too close and gravitationally disrupt a planetary system, flinging worlds into icy interstellar space.







Such a civilization would enjoy a very different environment than our own. The nearest star to our solar system is four light-years, or 24 trillion miles, away. In contrast, the nearest star within a globular cluster could be about 20 times closer — just 1 trillion miles away. This would make interstellar communication and exploration significantly easier.



The Daily Galaxy via Harvard University

Image credits: 


"The Galaxy" in Your Inbox, Free, Daily