Solar flare
Nasa's Solar Dynamics Observatory captures massive X-class solar flares NASA/GSFC/SDO

Humanity may witness an enormous solar flare within the next 100 years, which has the potential to cause huge economic and technological damage, according to researchers from Harvard University.

While they note that there are many uncertainties in predicting such events, in a new study published in the Astrophysical Journal, they say the risks have not been "sufficiently appreciated". In the event such a flare does occur, it could potentially knock out power systems, satellite communications and even the internet.

"The sun is usually thought of as a friend and the source of life, but it could also be the opposite," Avi Loeb from Harvard University told New Scientist. "It just depends on circumstances."

For the study, Loeb and Manasvi Lingam, examined the ramifications arising from superflares on the evolutionary history of the Earth, other planets in the solar system and exoplanets.

They suggest that the most extreme solar flares – known as superflares – could occur every 20 million years in stars like our sun. These can be 10,000 times as powerful as normal solar flares; so powerful in fact that if one occurred on Earth, it could potentially cause a mass extinction.

However, a less intense but still potentially damaging flare may yet occur within the next century. Previous studies have suggested that such an event will likely take place every 250 to 500 years.

In 1859 a powerful solar flare caused telephone wires to burst into flames while auroras were seen as far south as Cuba and Hawaii. But in today's technology-reliant society, a comparable event would be far more damaging.

"Back then, there was not very much technology so the damage was not very significant, but if it happened in the modern world, the damage could be trillions of dollars," said Loeb. "A flare like that today could shut down all the power grids, all the computers, all the cooling systems on nuclear reactors. A lot of things could go bad."

A solar flare is when the sun ejects clouds of electrons, ions and atoms, as well as electromagnetic waves, into outer space causing a sudden flash and an increase in the star's brightness. It usually takes a day or two for this material to reach the Earth.