The giant sunspot was captured on camera by NASA’s Solar Dynamics Observatory as it swelled to enormous proportions over the 48 hours spanning Tuesday and Wednesday (Feb. 19 and 20). SDO is one of several spacecraft that constantly monitor the sun’s space weather environment.

“It has grown to over six Earth diameters across, but its full extent is hard to judge since the spot lies on a sphere, not a flat disk,” wrote NASA spokeswoman Karen Fox, of the agency’s Goddard Space Flight Center in Greenbelt, Md., in an image description.

The sunspot region is actually a collection of dark blemishes on the surface of the sun that evolved rapidly over the last two days. Sunspots form from shifting magnetic fields at the sun’s surface, and are actually cooler than their surrounding solar material.