Sunspot AR1620 doubled in size again yesterday. It is now a behemoth almost 10 times as wide as Earth. A movie from NASA’s Solar Dynamics Observatory shows the sunspot materializing over the past 48 hours:
So far the sunspot has been relatively quiet, producing no strong flares. However, the sunspot’s magnetic field is rapidly changing as the sunspot grows, and rapidly-changing magnetic fields have a tendency to reconnect and erupt. NOAA forecasters estimate a 35% chance of M-class eruptions in the next 24 hours