The largest complex of sunspots recorded in over a decade has recently rotated into view from the far side of the Sun, and is currently in a position that could expose Earth to a major solar event, if the cluster were to generate one. While it is unlikely to produce a solar storm of comparable magnitude, this cluster is similar in size to the sunspot group that erupted in an X45 solar flare that triggered the Carrington Event, the most intense geomagnetic storm on record that, if it were to occur today, could cause massive damage to our electrical and communications networks.

Designated AR 4294-4296, this current cluster formed from the interconnection of two separate sunspot groups (4294 and 4296), and became visible when the Sun rotated the region into view on November 28. The cluster is expansive enough that some of the individual spots are large enough for an Earth-sized planet to pass through; in terms of the total surface area, this cluster is about 90 percent of the size of the sunspot complex recorded by Richard Carrington in September 1859.

On September 1 of that year Carrington’s cluster produced an unprecedented x45-magnitude solar flare that released a powerful coronal mass ejection (CME) that reached Earth less than 18 hours later, setting off a geomagnetic storm that caused auroral displays as far south as the tropics, caused fires in telegraph stations and generated enough power in the communications network for telegraph operators to send messages to one-another, even with their batteries disconnected. It is estimated that if such a storm were to occur today, it would wreak havoc on our modern electrical infrastructure, possibly causing long-term blackouts across much of our civilization.

Thankfully, AR 4294-4296 is unlikely to produce an event of that magnitude: events such as the 1859 solar storm are exceedingly rare, and the power of any given solar storm doesn’t appear to correlate to the size of the sunspots it erupts from. But the current solar cycle has been unexpectedly active, surprising solar researcherswho predicted solar cycle 25 would follow the half century-long trend of a decline in solar activity.

Regardless, it would be unwise to let our guard down, as the Carrington Event occurred during an otherwise-average solar cycle. Whitley outlines the danger presented by solar storms of that magnitude—and what needs to be done to weather such a storm—in his 2012 ebook Solar Flares: What You Need to Know.