"The idea is if a planet has life, like Earth, and if you hit it with an asteroid, it will create debris, some of which will escape into space," said astronomer Mauri Valtonen of the University of Turku in Finland. "And if the debris is big enough, like 1 meter across, it can shield life inside from radiation, and that life can survive inside for millions of years until that debris lands somewhere. If it happens to land on a planet with suitable conditions, life can start there."
The sun is thought to have formed around 4.5 billion years ago within a cluster of thousands of baby stars. After around 1 billion years, this cluster broke up and the sibling stars went their separate ways. But before that point, researchers say, some of these stars may have shared life in the form of bacteria or DNA molecules.
That means that somewhere out there in the galaxy might be your long-lost cousin.
On the other hand research suggests it's equally possible that Earth itself was seeded with life in such a manner.
A recent study recorded the positions and motions of more than 100,000 stars. Picking out those stars with radial velocities known to be similar to the sun's. Identified are two promising stars, called HIP 87382 and HIP 47399, that also had the same metal content and were at the same evolutionary stage as the sun. According to the researchers' analysis, there are a few percentage points of probability that these two were born in the same cluster as our sun. Both are about 100 light-years from Earth now.