Science:
Every so often, a subatomic particle crashes into Earth's
atmosphere packing as much energy as a large hailstone.
Physicists have struggled for decades to determine where such
ultrahigh-energy cosmic rays come from, what they consist of,
and how they are accelerated to energies 100 million times
greater than particle accelerators have reached. Now answers
may be in sight. Ultra-high-energy cosmic rays appear to come
from the neighborhoods of certain nearby churning galaxies,
physicists working with the gigantic Pierre Auger Observatory
in western Argentina
report
in
Science this week (page 938). The finding marks a
first big step toward explaining the mysterious particles, say
researchers
to
Science's Adrian Cho.
