The sun may spit out giant solar flares more often than we thought

A survey of more than 56,000 sun-like stars reveals that “superflares” that are linked to bursts of radiation which play havoc with electronics on Earth may happen every 100 to 200 years and we may be overdue one

By Alex Wilkins

12 December 2024

This relatively small solar flare from October – the bright flash in the centre spotted by NASA’s Solar Dynamics Observatory – would be dwarfed by a superflare

NASA/SDO

The sun may produce extremely powerful bursts of radiation more frequently than we thought. Such “superflares” seem to happen as often as once a century, according to a survey of sun-like stars, and might be accompanied by particle storms that could have devastating consequences for electronics on Earth. As the last big solar storm to hit Earth was 165 years ago, we might be in line for another soon, but it is uncertain how similar the sun is to these other stars.

Read more

Dyson spheres: How to spot an alien megastructure

While direct measurements of the sun’s activity only started towards the middle of the 20th century, there is earlier evidence of solar storms. We know that in 1859, our star produced an extremely powerful solar flare, a burst of light radiation. These are often associated with a subsequent coronal mass ejection (CME), a bubble of magnetised plasma particles that shoots out into space.

Advertisement

That flare was indeed followed by a CME that struck Earth and caused an intense geomagnetic storm, which was recorded by astronomers at the time, and is now known as the Carrington event. If this happened today, it could knock out communication systems and power grids.

There is also evidence on Earth of much more powerful storms long before the Carrington event. Assessments of radioactive forms of carbon in tree rings and ice cores suggest that Earth has occasionally been showered with very high-energy particles over periods of several days, but it is unclear whether these came from one-off, massive solar outbursts, or from several smaller ones. It is also uncertain if the sun can produce flares and particle storms so large in a single outburst.

The frequency of these signs on Earth, as well as superflares that astronomers have recorded on other stars, suggested that these giant bursts tend to occur many hundreds to thousands of years apart.