
Global Space News: Could our Sun produce a superflare?
This last year has seen our night skies lit by the greens and pinks of the northern and southern lights, with several displays of the aurora extending to low latitudes far from the Earth’s poles. The source of these vivid nights is heightened activity from our Sun, which is currently at the peak of its eleven year cycle of eruptions. This “Solar Cycle” is marked by a periodic rise and fall in the number of dark sunspots that dance over the Sun’s surface, accompanied by solar flares and ejections of plasma that blast high energy particles into interplanetary space. When these particles reach Earth, the particles are caught in our planet’s magnetic field, spiralling inwards to strike our atmosphere in an explosion of light.

For most of our history, the impact of solar activity has been limited to the lights of the aurora, extending during times of heightened solar activity. But what if the Sun were to produce a much larger eruption?
“Superflares, massive explosions much larger than our Sun’s solar flares, are known to occur in stars similar to our Sun,” explains Toriumi Shin, Associate Professor in the Department of Solar System Science.
A recent study led by researchers at the Max-Planck-Institut fÃŒr Sonnensystemforschung in Germany and published in the international journal “Science”, surveyed 56,000 stars that are similar to our Sun that had been observed by the NASA Kepler Space Telescope. The team identified almost 3,000 stellar flares with energies a factor of a hundred to a thousand greater than a typical solar flare.
“The new analysis shows that superflares occur at a much higher rate than previously estimated, about once per star per century,” notes Toriumi. “The SOLAR-C satellite, the extreme ultraviolet spectroscopy mission led by ISAS/JAXA, will observe solar flares in great detail and study how they occur. I hope that SOLAR-C’s findings will also help elucidate the mechanism of superflares.”
Following on from the Hinode (SOLAR-B) spacecraft which was launched in 2006, SOLAR-C is the next generation solar mission under development at JAXA and the National Astronomical Observatory of Japan (NAOJ). SOLAR-C will study the Sun in the ultraviolet, allowing a view of the immensely hot outer solar layers from the 10,000 K[*] chromosphere, the 1,000,000 K corona and onto the 15,000,000 K solar flares. A key science goal will be to understand the mechanism for how solar flares occur; an observation that requires not only the ability to view the hot gas, but also the resolution to follow these explosive events that can release energies millions of times greater than our largest earthquakes in just minutes to hours.
Particularly large bursts of stellar activity can result in more than a light show. The high energy solar energetic particles can threaten satellites, and the health and lives humans who have dared to venture into space. It is something that must be carefully watched as we look towards returning humans to the Moon.

Solar energetic particles (SEPs) generated by solar flares are one factor that endangers astronauts’ lives on the Moon,” explains Shinohara Iku, Department of Solar System Sciences. “Space weather to predict how SEPs generated by the Sun reach the Moon is an important research topic for Japan in the era when Japanese astronauts are landing on the Moon. JAXA has a wide range of observation tools that monitor from the Sun to geospace, including the solar observatories Hinode and SOLAR-C, Mercury explorer BepiColombo/Mio, and geospace explorer, Arase. With this wealth of data, we can investigate how SEPs travel through interplanetary space and impact the lunar surface. We believe it is essential for realising lunar weather forecasting, utilising our extensive datasets and other research resources in Japan.
If the rate of superflares observed in this study also applies to the Sun, then a massive superflare could erupt that exceeds the energy of any previous flare since the start of the space age by an order of magnitude. As plans progress to expand human presence in space, increasing our understanding the origin of solar flares and ability to predict dangerous events could be essential before we can ever call another world “home”.
[*] 0 K (kelvin) is -273.15°C, but at the extreme temperatures in the Sun’s outer layers, the units can be considered approximately equivalent!
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Further information:
Journal paper: Sun-like stars produce superflares roughly once per century, Vasilyev et al. 2024 (external site)
SOLAR-C website and X account (external site)