The discovery of alien life would be revolutionary. But what if we uncovered it on two—or even seven—planets all orbiting the same star?
That’s the tantalizing possibility offered by the cosmic grouping called TRAPPIST-1, where seven Earth-size worlds circle a star roughly 39 light-years away. According to a new study, those planets are packed so tightly around their stellar host that the seeds of life could be hopping between them with ease.
The study, conducted by Manasvi Lingam and Abraham Loeb of the Harvard-Smithsonian Center for Astrophysics, is based on a theory known as panspermia, which in turn is based on the fact that planetary debris can be swapped between the worlds in our solar system. This is especially true for neighboring rocky planets—for instance, asteroid strikes have sent fragments of Mars crash-landing onto Earth.
Panspermia takes this a step further and suggests that life could catch a ride on that debris, hitchhiking from one planet to the next. It might sound wild, but recent research shows that some extreme forms of life can survive conditions akin to an interplanetary journey. Some scientists even argue that the seeds of life on Earth could have come from Mars.