Powerful stellar explosions may have caused mass extinctions on Earth and could also have prevented life from appearing on other planets until 5 billion years ago—and then only in the outskirts of galaxies.
A gamma-ray burst (GRB) is an intense flash of radiation from a dying star that could damage or eliminate life on a planet light years away. A pair of astrophysicists has now analyzed the latest astronomical data to update previous estimates of the likelihood that a GRB affected life on Earth. They found that there’s a
60%
chance that a GRB caused an extinction-level event within the past billion years. Looking beyond Earth, the team found that life is more likely to appear in the outer regions of a galaxy, where GRBs are less common, and that GRBs may have made much of the Universe unfriendly to life until about