Reconnection is most efficient when the IMF has a component that is directed southward-that is, opposite to the northward direction of the earth's magnetic field at the dayside of the magnetosphere.

Loggerhead turtles sense latitude by the planet's magnetic field intensity, and new research finds they're good at determining their longitude too, probably via the field's inclination.

The researchers believe that the loggerheads create their mental magnetic map by combining information about the angle of the magnetic field with its intensity.