Did you know that the geographic north pole is actually the south pole of the Earth's magnetic field, which is why the magnetic needle always points to the north pole of the compass? But about 1.1 million years ago, the magnetic needle would point the opposite direction, the today's compass, the magnetic south pole will point to the geographic south pole and the same goes with the magnetic north pole. So this situation concludes that the Earth's magnetic field swaps whenever it wants to for no apparent reason.

Geologists found out how and when it was swapped by observing the cooled molten rocks on the Earth's surface. The solidified lava contains iron that tends to line up with the Earth's magnetic field. They measured the past Earth's magnetic field with sensitive magnetic measuring equipment and usually used on the ocean floor's boundaries, where the old molten rocks can be found. In the 1950s and 1960s, each conducted measurement confirmed the same conclusion that there are numerous flip-flopping happened. There are at least hundreds of evidence of magnetic field reversals. Unfortunately, they could not determine the pattern of the timing when the magnetic field reverses, so they are uncertain when could be the next flip. Some believed we could be at the age of , a period of about 40 million years without a single reversal.

But this natural phenomenon is not as fun as we think, it might cause a worldwide inconvenience if it will happen today, but not too apocalyptic. During reversals, the magnetic field weakens until it's almost gone then gradually returns in an opposite orientation. Without the magnetic field, nothing will protect us from extreme forms of interstellar and solar radiation. Satellites in low earth orbit and electronics on Earth's surface might stop working due to decreasing power grids. Living things might suffer from extra bad sunburns or increased rates of cancer due to cell-damaging radiation. And Santa probably, cannot find his way home!

Scary right?