Deep under the ice in Greenland and Antarctica, scientists have found evidence of a huge solar 'tsunami' that once crashed into the Earth's atmosphere more than 9,000 years ago.
This age-old superstorm was triggered by a wave of hot plasma and magnetism from the Sun, and it is significantly larger than anything we have recorded in recent history.
The results have caused scientists to worry about our ability to predict when the Sun will release next time.
Solar storms on Earth occur every few years when the Sun's activity is at its peak, but this old superstorm is on a completely different scale and it seems to have hit a quiet phase of the solar cycle.
In recent years, scientists have warned that we are completely unprepared for a solar storm of this magnitude. Experts still have not figured out how to predict these rare but catastrophic events, and the infrastructure we have built today is unusually vulnerable to geomagnetic precipitation.
If one of these superstorms hits tomorrow, it could affect satellites and astronauts in orbit, as well as air traffic control, power grids and submarine cables, which will trigger travel restrictions, power outages and global Internet outages that could last for months.
Just consider what happened in 1859, when we had far less infrastructure at stake. The Carrington event was a solar storm that was so severe that it collapsed telegraph systems in Europe and North America, while also triggering the Northern Lights all over the world, from Australia to Hawaii to China to Mexico.
But what happened 9,000 years ago could give the infamous event a run for its money.
A solar flare or a coronal mass ejection is what usually triggers a solar storm. The latter occurs when the sun barks about a billion tons of energetic particles into space, and if the barrel is large enough, these particles can hit the Earth's atmosphere in as little as 15 hours.
The reaction produces several radioactive nuclides, such as carbon-14, beryllium-10 and chloro-36.
Traces of these distinct isotopes, frozen in ice or trapped in sediment, can therefore help us illuminate the history of extreme solar events on Earth so that we can better understand how often they occur.
The recent ice cores analyzed from Greenland and Antarctica have now revealed some of the largest beryllium-10 and chlorine-36 production peaks ever found in Earth's distant past.
The evidence strongly suggests that there was an extreme solar storm around 9,125 years before the present.
"This is time-consuming and expensive analysis work," says geologist Raimund Muscheler from Lund University in Sweden.
"Therefore, we were pleasantly surprised when we found such a peak indicating an unprecedented giant solar storm associated with low solar activity."
Judging by the ratio of chlorine-36 to beryllium-10 isotopes, this event may have even been greater than the largest solar storm recorded to date in other ice cores and tree rings, dating to the year 774.
Both of these prehistoric storms were far greater than anything we have seen since the 1950s, "and thus pose a hitherto underestimated threat to our society," according to the authors of the paper.
"These huge storms are currently not adequately included in risk assessments," Muscheler says.
"It is of the utmost importance to analyze what these events may mean for today's technology and how we can protect ourselves."
Otherwise, the Sun could catch us completely unprepared.
The study was published in Nature communication.