Tabby's Star

1,500 light years away, in the direction of Cygnus, lies a star that probably doesn’t host an advanced civilization.

Glancing up at countless other barren stars, you might think this was a non-story. In fact, it’s big news.

In September, astronomers from the Kepler mission published a description of the star (officially designated KIC 8462852, unofficially “Tabby's Star”, after Tabetha Boyajian, the lead author of the paper). It’s around the same size as the sun, but with a bizarre “light curve”—variations in the intensity of the light received from the star. A planet the size of Jupiter, passing in front of such a star, might be expected to dim its light about 1%. This star’s light has been observed to drop 22% in asymmetric and aperiodic dimming events unlike anything else seen in the Kepler mission.

Possible explanations—none completely satisfactory—include a swarm of disintegrating comets, or a disk of matter surrounding the star (which looks far too old to retain such a disk). Jason Wright, an astronomer at Penn State University who was consulted by Boyajian about the problem, proposed an unlikely but intriguing possibility: that the dimming effect is caused by a swarm of Dyson Spheres—hypothetical megastructures that advanced civilizations might build to capture energy from their stars.

There are three reasons why all this is important.

First, something interesting is happening around Tabby’s star. Even if it’s not a megastructure, investigating it will surely increase our knowledge of stars, the formation of planets, or both.

Second, the anomaly was not discovered by astronomers. It was flagged up by “citizen scientists” from the Planet Hunters project, scanning the Kepler data for signs of unknown extrasolar planets. This is a significant development in 21st-century science: its gradual broadening beyond academia, research institutions and corporations to include the general public. Open data has allowed ordinary people to sample the immense harvest of data collected by instruments like the Kepler telescope. Distributed computing enables them to use their personal computer power to analyse that data. And programs such as Planet Hunters invite them to use their critical faculties to find interesting patterns. We are witnessing the early steps of a revolution in the scientific process: the growth of a planet-wide network of specialists, laypeople, and computers, collaborating to create scientific knowledge.

Third, the mere fact that astronomers can investigate a specific planet as a candidate for intelligent life illustrates how the Kepler mission has transformed astrobiology—from a heroic but marginal pursuit into a popular and rapidly maturing science. Seven years ago, many believed that potentially habitable planets were vanishingly rare. Today, to suggest that there are billions—in our galaxy alone—is a conservative estimate. And more and more evidence—such as the ubiquity of organic molecules in environments beyond our solar system—suggests that life may bloom on some of these planets.

Intelligent life, though, remains a great unknown. We know that it has arisen once in at least 3.5 billion years of evolution on Earth. But extrapolating from Earth to the universe is guesswork.

Yet after Kepler, theories about civilizations beyond Earth are no longer stabs in the dark. Now, as Tabby’s Star shows us, the scope for serious science has expanded enormously. Astronomers and committed non-scientists can study large and growing bodies of data for interesting patterns. When they find them, they can focus the wide resources of modern astronomy—from radio searches to optical spectroscopy to computational modeling—on individual candidate planets.

That means that this century, we may finally have a serious chance of resolving Fermi’s Paradox: Where is everybody?

 There is no bigger question out there.