As the sun's energy rises and falls, so goes the Earth's atmosphere, a new study suggests.
These fluctuations in the sun's energy explain a recent partial
collapse of the Earth's upper atmosphere, which had previously puzzled scientists.
A sharp drop in the sun's ultraviolet radiation levels triggered the collapse, according to the new study, detailed in the Aug. 25 edition of the journal Geophysical Research Letters. The researchers also found that the sun's magnetic cycle, which produces differing numbers of sunspots over an approximately 11-year cycle, may vary more than previously thought.
"Our work demonstrates that the
solar cycle not only varies on the typical 11-year time scale, but also can vary from one solar minimum to another," said study team member Stanley Solomon of the National Center for Atmospheric Research (NCAR) in Boulder, Colo. "All solar minima are not equal."
The findings may have implications for orbiting satellites, as well as for the International Space Station.