As the sun revolves, the sunspot activity that has temporarily faced away from the Earth has started directly affecting us again. Giant sunspots 486 and 488 are moving into a position where they can once again direct solar explosions towards the Earth. Meanwhile, sunspot 484 has developed a complex magnetic field, meaning it can also give out X-class solar flares, so strong sunspot activity is predicted for the next few days.

We can tell the history of the Earth's magnetic field by analyzing clay pots from the distant past. During high-temperature firing, iron minerals in the clay record the exact state of Earth's magnetic field at that precise moment. Geologist John Shaw says, "When we plot the results from the ceramics, we see a rapid fall as we come toward the present day. The rate of change is higher over the last 300 years than it has been for any time in the past 5,000 years. It's going from a strong field down to a weak field, and it's doing so very quickly."

At the present rate, our magnetic field could be gone within a few hundred years, exposing the planet to blasts of charged particles from space. Scientists think this is what may have happened to Mars, which suffered a magnetic crisis four billion years ago and has had no magnetic field—and probably no life—ever since.

From looking at ancient lava flows in Hawaii, researchers know that the Earth's magnetic poles have reversed in the past. Geologist Mike Fuller says, "When we go back about 700,000 years, we find an incredible phenomenon. Suddenly the rocks are magnetized backwards. Instead of them being magnetized to the north like today's field, they are magnetized to the south." A pole flip seems to happen every 250,000 years, meaning we're long overdue for another one.