Variations in growth rate match today’s 11-year solar cycle, study claims
L. Luthardt and R. Rößler
The sun has been in the same routine for at least 290 million years, new research suggests.
Ancient tree rings from the Permian period record a roughly 11-year cycle of wet and dry periods, climate fluctuations caused by the ebbing and flowing of solar activity, researchers propose January 9 in Geology. The discovery would push back the earliest evidence of today’s 11-year solar cycle by tens of millions of years.
“The sun has apparently been doing what it’s been doing today for a long time,” says Nat Gopalswamy, a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who was not involved in the study.
Around every 11 years, the sun’s brightness and the frequency of sunspots and solar flares completes one round of waxing and waning. These solar changes alter the intensity of sunlight reaching Earth and, some scientists