Solar Storms

A drawing of the aurora observed from Nagoya, Japan, on September 17, 1770

A drawing of the aurora observed from Nagoya, Japan, on September 17, 1770

"The sky seemed to be burning", one diarist in Japan writes in early September 1859.

The sky glowed red, and people assumed it was the light of distant fires that were burning in some unknown location.

This was how auroras were perceived.

People feared the world would end, and would dedicated dances and prayers.

Today, people travel to the northern parts of the world to see the aurora borealis.

And we understand that this happens because of charged particles from the sun travelling down to Earth's magnetic field lines, interacting with the gases in our atmosphere.

Green and red light is from interactions with oxygen; blue and purple by nitrogen.

Usually auroras are only visible at the poles, but during severe geomagnetic storms, auroras can be seen closer to the equator.

The 1859 event is the most severe solar storm event observed in our time. It sparked fires at telegraph offices and shocked operators. And auroras were visible in low-altitude places like Hawaii.

A solar storm of that magnitude today would be a catastrophe. Satellites, communication networks, and the power grid could all be destroyed. And if this happens in winter, there wouldn't be any power at all.

One agency estimates the cost of disruptions and repairs after such a severe storm could reach $2 trillion.

Now researchers are studying ancient text, to build a more accurate understanding of the solar cycle.

They identified the earliest known aurora in the Chinese Bamboo Annals, which dates to the tenth century B.C.E.

This is vital as we're approaching a period when the sun's magnetic field will be unstable and solar storms will be more frequent, which scientists call a Solar maximum. It's predicted to happen sometime in 2025.

Unearthing historical observations can help us figure out whether what we observe now is unusual, or just the sun doing it's thing.

"The past is the key to the present (and future)"