

"The causal chain is the following: the changes in Earth rotation are simply reflecting the changes in angular momentum of the Earth's atmosphere, more precisely the integral of zonal winds. And it has been suggested that cosmic rays influence cloud condensation nuclei formation. If you change the cloud cover by say 10-percent, you change the amount of energy reflected by cloud tops by 8 Watts per square meter, which is very significant in the Earth's radiative budget. So this is the suggested link: cosmic rays affect cloud cover, which affects the atmosphere's energy budget, which may alter the wind speeds and organization, which changes the Earth's angular momentum hence (length of day)."

Of course, 30-percent of that change only amounts to a few tenths of a millisecond, so you'd never actually notice it, but what's more compelling (read 'very highly controversial') is the potential for cosmic-rays to have such a profound affect.Courtillot and his colleagues have been among those championing a radical theory that cosmic rays can impact the formation of clouds and in turn, play a major part in climate changes. But how could cosmic rays possibly change the speed of our planet's rotation?Here's how Courtillot explained it to me in an email:It may sound like a reach (and relationships don't prove causation), but other physicists have claimed that the sun's magnetic field could potentially beat back cosmic rays and slow the rate at which they reach Earth. So when solar activity decreases there's less to deflect the cosmic rays and they can again reach Earth in greater numbers, potentially leading to a substantial enough change in winds to affect Earth's angular momentum.