A new study shows that the Sun is, in principle, capable of flares significantly more powerful than all events directly measured in the modern era. Researchers linked the sizes of the largest sunspots to the possible energy of flares and concluded that areas of such a scale can, in rare cases, be the source of superflares.
Scientists compared the sizes of active regions with the energy of the 300 most powerful flares recorded by the Solar Dynamics Observatory between 2010 and 2016. Researchers found a statistical correlation: larger active regions are, on average, capable of generating more energetic flares.
The most impressive example was a giant sunspot observed on April 8, 1947. Its diameter was approximately 40 times that of Earth, and its area was about 0.6% of the Sun's visible disk. According to researchers' calculations, a sunspot of this scale could potentially generate a flare with an energy of several × 10³⁴ ergs.
But this is where the main paradox arises. The 1947 sunspot itself did not produce a superflare, and nothing comparable has yet been recorded on the Sun in the era of direct measurements. However, events of such power are regularly detected on other Sun-like stars.
This does not mean that the Sun is preparing such an eruption or that a superflare will necessarily occur. The study shows something else: physically, our star is capable of creating active regions of suitable scale, which means that the solar flares known to humanity may be far from the upper limit of its capabilities.
Sunspots have been systematically observed for about 400 years, but accurate measurements of flare energy cover only a relatively short space era. Compared to the Sun's age of about 4.6 billion years, this period is practically negligible — therefore, the absence of superflares in modern history does not yet prove that they did not occur earlier.