Northern Exposure: The inhospitable side of the galaxy?

The solar system’s periodic visits to the northern side of the Milky Way expose life on Earth to extra cosmic rays that have caused catastrophic mass extinctions, two astrophysicists propose.

COSMIC PERIL. As the Milky Way (represented here by a similar galaxy) whirls around, the solar system’s wobbly trajectory (green curve) periodically exposes Earth to harsh cosmic rays.