THE MOST ACTIVE SUNSPOT IN YEARS: Fast-growing sunspot AR3663 has quickly become the most active sunspot of Solar Cycle 25. Today alone it has unleashed two X-flares and six M-class flares. This interest-compressed movie from the Solar Dynamics Observatory shows 12 hours of crackling action. Each of these flares has created a brief but deep radio blackout on Earth, causing loss of signal at frequencies below 30 MHz. These are events easily noticed by ham radio operators, aviators and mariners us

• Sunspot Light-Bridges • A Bridge from the Photosphere to the Corona? Light-bridges are lanes of bright material that divide the umbra in a sunspot. They are often observed during the break-up of sunspots and therefore can represent the re-establishment of convection which is normally inhibited by the sunspot's strong magnetic field. Their increased brightness suggests a higher plasma temperature than in the surrounding umbra, and they have been shown to display significantly enhanced chromosph