January 21, 2016
In 1612 Galileo completed a series of sunspot drawings which has inspired over 400 years of drawings of sunspots. At the National Solar Observatory solar drawings are still being made. In the early 1600’s there was a question as to whether sunspots were, in fact, on the Sun or transiting bodies. The foreshortening of sunspots near the Sun’s limb in Galileo’s drawings proved that the spots were on the sun and not transiting celestial bodies.
Today sunspots are studied because flares and Coronal Mass Ejections associated with active regions have enough energy to disrupt our satellites, our communication systems, and our power grid. Another Carrington Event, the solar storm of 1859 “… would devastate (our) modern world.”
In the picture above active regions 484, 486, and 488 can be seen. AR484 produced two X-class solar flares. AR484 was the largest active region of the last solar cycle, cycle 23. It produced three X-class solar flares including an X-28 solar flare that was the strongest solar flare in the last solar cycle. These solar active regions brought us the Halloween geomagnetic storm and auroras of 2003. The good news is that NASA has a plan to provide a warning system to protect us from the effect of such storms.