Earth & Space Science News By Aaron Sidder 5 April 2019
The Sun undergoes a magnetic metamorphosis every 11 years, when the celestial body flips its magnetic poles: North becomes south, and south becomes north. The Sun is currently in solar cycle (SC) 24, which began in June 2009. No cycle is the same: The length can vary from 9 to nearly 14 years, and the degree of solar activity fluctuates as well. Within each solar cycle, the frequency of sunspots and flares ebbs and flows in response to the changing magnetic field around the star.
The thermosphere, one of the outer layers of Earth’s atmosphere, is particularly sensitive to variation in solar activity. The thermosphere forms about 100 kilometers (62 miles) above our heads and extends for several hundred kilometers above that. It absorbs much of the X-ray and ultraviolet radiation from the Sun. During periods of high solar activity, the X-ray and ultraviolet radiation from the Sun increase, and the thermosphere swells as it sops up this increase in energy from the Sun. As the Sun approaches solar minimum, the thermosphere cools and shrinks as the intensity of the X-ray and ultraviolet radiation decreases. Since the International Space Station and many satellites orbit through this layer, changes in thermospheric boundaries and densities can affect their operation and the maintenance of their orbits.
More:
https://eos.org/research-spotlights/the-thermosphere-responds-to-a-weaker-than-normal-solar-cycle
