Although the sun’s current 11-year cycle of activity is one of the quietest ever recorded, this Oct. 20 image (left) is anything but calm. The composite combines different views of extreme ultraviolet light captured by NASA’s space-based Solar Dynamics Observatory. The coronal loops — massive magnetic arches of hot gas — sizzle at 1.8 million degrees Fahrenheit (yellow), while plumes of plasma (red) simmer at a relatively cool 90,000 F.
In October, the area known as active region 12192 (the bright patch on the left side of the main image) spawned the largest sunspot group in 24 years. According to NASA solar scientist C. Alex Young, the region is unusual because it produced fairly large solar flares but not the huge coronal mass ejections that typically occur at the same time, sometimes damaging satellites.