We’ve discovered alien life! Probably. Possibly. Maybe. Okay, fine, we almost certainly have not discovered alien life but we have found an interesting anomaly worth further study. One of the most successful citizen science projects of all time has been the incredibly exciting Planet Hunters project where you yourself can go and try to find a new planet out there in the galaxy; I myself have lost a number of evenings classifying traces. It’s all based around the Kepler space telescope. Kepler spent several years staring relentlessly at about 150,000 stars in an average piece of sky. It was measuring the brightness of all those stars and looking for tiny variations in the brightness observed. If a dip in brightness is seen then it is possible that it was caused by a planet moving in front of the star and briefly making it appear less luminous. If the same pattern was seen at a regular, predictable interval then that was taken as pretty good confirmation that the star has at least one planet orbiting it. This is known as the Transit Method of detecting planets. Thirty years ago we didn’t know of any exoplanets, now we have a catalogue of hundreds.
Four years ago one trace in particular started making waves, if you’ll forgive a lame graph-based pun. The trace in question did not yield the usual periodic regular dip; instead the time interval was irregular and also changed in intensity. This prompted the team to observe the star more closely, over a long period of time and with a whole suite of different instruments so they could learn as much as they could about what’s going on there. The short answer is: we don’t know. There are several possibilities, though, and this is what the paper, published in Arxiv, goes into detail on.
The less likely option is that this intermittent blocking of the starlight is caused by clouds of dust and proto-planets that haven’t yet formed around the star, much like our system would have looked 4.5 billion years or so ago. Except this isn’t a young star, it’s a middle aged one much like our own that should easily have cleared out it’s near neighbourhood by now. Another ruled out option is some kind of mix up or error in the data itself, but all known possible artefacts or defects have been ruled out. There are various other possibilities but the authors conclude that the most likely is that there are large lumps of broken up comet irregularly orbiting the star; this could have been caused by a rogue star passing nearby the one being observed and dragging comets along with it into eccentric orbits.
The paper, though, only covers ‘natural’ explanations for the phenomenon. Unmentioned in the paper but being pursued by the scientists through linking up with the SETI project is the prospect of something altogether more exciting. By their own admission it is exceedingly unlikely yet tantalisingly possible that the effect is caused by ‘alien-made’ structures orbiting the star harvesting it’s energy like some kind of crude Dyson Sphere. The team have booked time on a telescope array that will hopefully detect any radio waves coming from the area. If they do, and if they bear the hall marks of waves created by artificial technology then, well, it would be really quite exciting, wouldn’t it? How we would ever conclusively prove it was alien life I have no idea, it might not even be possible; it is, however, at least worth a look.