Earth’s magnetic north is not static. Like an anchorless buoy pushed by ocean waves, the magnetic field is constantly on the move as liquid iron sloshes around in the planet’s outer core.

Earth’s north pole comes in two forms: true north and magnetic north. True north refers to the geographic north pole, the fixed point where Earth’s rotational axis meets its surface.

Here is everything to know about the northern lights this week, including whether they will be visible in Arizona. The northern lights will actually be visible in 15 states tonight: Alaska. Washington ...