By the time the giant spot on the sun rotated into view on October 18, it was already 80,000 miles wide, big enough to fit all of Jupiter, big enough to lay 10 Earths, side by side, across. It is the largest spot the sun has harbored in 24 years.

But while most erupting sunspots lob chunks of plasma outward in events called coronal mass ejections, this one’s keeping its plasma close to the surface.