Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. But over South America and the southern Atlantic Ocean, an unusually weak spot in the field — called the South Atlantic Anomaly, or SAA — allows these particles to dip closer to the surface than normal.Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. But over South America and the southern Atlantic Ocean, an unusually weak spot in the field — called the South Atlantic Anomaly, or SAA — allows these particles to dip closer to the surface than normal.
