The Sun has been feisty this year. It’s produced some monster storms that have pelted Earth with radiation and charged particles. That’s disrupted some communications, air travel, and other daily activities.

There’s evidence that the Sun has been much feistier in centuries past. If such major outbursts happened today, they could be really bad for modern technology. But the big ones in the past are good for archaeology. They’re helping scientists nail down the dates of some ancient human activities.

The Sun is especially active every 11 years or so. It blasts out giant clouds of charged particles. When the particles hit the atmosphere, they create cascades of other particles. That includes a radioactive form of carbon. Trees take up some of this carbon. The more active the Sun is, the more they absorb.

By analyzing the ratio of different forms of carbon in tree rings, scientists can determine which years were especially “stormy.” And that gives them a way to date human settlements.

Earlier this year, for example, a team studied rings in logs that were used to make houses and other structures at a site in Greece. The scientists found rings that recorded a busy year for solar activity. It corresponded to a previously discovered peak, in 5259 BC. Counting all of the tree rings showed the site had been inhabited for at least a couple of hundred years – including a time with an especially feisty Sun.

Script by Damond Benningfield