Most people don’t know that Earth’s magnetic field has a weak spot the size of the continental United States hovering over South America and the southern Atlantic Ocean.
We’re safe from any effects on the ground, but our satellites aren’t so lucky: When they zip through this magnetic anomaly, they are bombarded with radiation more intense than anywhere else in orbit. There is reason to believe that this dent in the magnetic field, called the South Atlantic Anomaly, is only getting bigger.
This anomaly is far from the only unusual feature of Earth’s magnetic field.