SPOTLESS SUN SPARKS PINK AURORAS: On Feb. 23rd the sun was completely blank (no sunspots) and NOAA classified solar activity as “very low.” Nevertheless, this happened:
“Despite the blank sun, we witnessed a beautiful display of auroras,” reports photographer Andrei Andritcu from Tromso, Norway. In addition to the usual green, the lights contained a vivid splash of pink.
In auroras, pink is a sign of nitrogen. Ordinary green auroras are caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth’s surface. Pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below.
Recent displays of pink and white auroras have coincided with spotless suns often enough to make observers wonder if there is a connection. E.g. perhaps solar wind emerging from the spotless sun is unusually penetrating. If so, we can expect to see more nitrogenous auroras in the years ahead. The sun is descending into a deep Solar Minimum, and the nadir (expected in 2019-2020) could be colored pink.