Opinion Top boffins reviewing data from a NASA satellite dedicated to probing the secrets of the Sun say that some solar flares directed towards Earth deliver much more energy than had previously been thought.
Solar flares are massive releases of radiation associated with sunspots. If they hit Earth, they can deliver large amounts of energy into the atmosphere: they can also damage or destroy satellites or probe craft in space, particularly where these are beyond some or all of the protective magnetic fields of Earth.
According to a statement issued yesterday by scientists investigating results from the orbiting Solar Dynamics Observatory (SDO), such flares carry much more energy than had been thought. The statement says:
Scientists have observed that radiation from solar flares sometimes continues for up to five hours beyond the initial minutes of the main phase of a solar flare occurrence. The new data also show that the total energy from this extended phase of the solar flare peak sometimes has more energy than that of the initial event.
On Nov 3, 2010, a solar flare was observed by SDO. If scientists had only measured the effects of the solar flare as it initially happened, the information would have resulted in underestimating the amount of energy shooting into Earth's atmosphere by 70 per cent. The new capability with SDO observations will provide a much more accurate estimation of the total energy input into Earth's environment.
"If we can get these new results into space weather prediction models, we should be able to more reliably forecast solar events and their effects on our communication and navigation systems on Earth," says Tom Woods of the University of Colorado, a scientist involved in the research.
Space weather is important stuff, as it can affect the accuracy of signals from navigation-and-timing satellites such as the GPS constellation – with potentially much wider effects than just introducing inaccuracy into satnavs.
What is not being mentioned here is the possibility of effects on the Earth's climate. The very idea that variations in the Sun can alter the environment on Earth has now become highly controversial, as it can distract from – or reduce the importance of – the issue of human-driven greenhouse gas emissions into the atmosphere.
Nonetheless, the revelation that some solar flares at least carry much more energy to Earth than had previously been thought is important, especially as many major solar physicists think that the Sun may be headed into a so-called "Maunder Minimum" like that seen from 1645 to 1715 – which would mean corresponding fewer solar flares and less warming energy reaching Earth. As NASA notes:
Although the observations were not as extensive as in later years, the Sun was in fact well observed during this time and this lack of sunspots is well documented. This period of solar inactivity also corresponds to a climatic period called the "Little Ice Age" when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes. There is evidence that the Sun has had similar periods of inactivity in the more distant past. The connection between solar activity and terrestrial climate is an area of ongoing research.
The latest SDO results would seem to indicate a greater cooling effect from a calming Sun than would previously have been expected by physicists.
Carbon-hating Greens would naturally point out at this stage that humanity still ought to curtail carbon emissions as even if the Minimum is coming, as at some point toward the end of the century the sunspots will begin to return and the planet will warm up again, perhaps disastrously if the air has been negligently stuffed with carbon in the meantime.
That could be a hard message to sell in the near future, though, with economic woes continuing, cheaply-carbon-powered developing economies to compete with, and bitterly cold winters possibly getting more frequent. With doomsday postponed well into the 2100s, it could be very difficult indeed to get anyone to care about it.
The new research is published here in The Astrophysical Journal. ®
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