NARRATOR: Even though the solar wind and storms are hitting Earth all the time, we usually don’t notice them. Thanks to our planet’s strong magnetic shield and thick atmosphere, most of the harmful rays and particles the Sun emits never make it to Earth’s life-friendly surface.

But most experts believe it’s only a matter of time before a huge solar storm overwhelms Earth’s natural defenses. After all, it’s happened before…

In 1859, newspapers in the U.S. reported widespread aurora sightings, some so strong they turned night into day. Based on these accounts and other evidence, scientists believe that back-to-back storms gave Earth the biggest solar blast ever recorded.

The storms created huge variations in Earth’s magnetic field; inducing currents in telegraph lines so strong they burned operators and started fires in offices.

What would happen if a similar storm hit us today? With societies so reliant on modern technology, the damage would be far worse. Blown transformers could take months to repair, leaving millions without electricity. And the damage would not be limited to our power grid.

J. TODD HOEKSEMA (Stanford University): More and more, we rely on technology that could be affected by the Sun: global positioning satellite, long distance communication, airplane tracking, astronauts in space. So there is an urgency in understanding what it is that the Sun is doing, what it’s gonna do next, and how can we prepare for that and respond to it?

NARRATOR: There’s nothing we can do to prevent huge storms from happening. But if we can get better at predicting and spotting them, we’ll buy time to take preventative measures and reduce the amount of damage they create.

So, will we be able to predict when the next megastorm will come?

COLLECTION OF SCIENTISTS: No… Maybe… No… Maybe… No…”

JIM GREEN (NASA Planetary Science): Maybe. And the reason why is we’ve learned so much about the Sun, we’re getting better at it, but we have a long way to go. And the more we look at some of these historic events, the more we get a deeper appreciation for what we need to know.