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Scientists say Sun capable of producing ‘superflares,’ – 1000 times stronger than any flare ever witnessed
May 2015 – SOLAR WEATHER – Could
the sun unleash a flare of such a magnitude that it dwarfs anything
that humans have ever observed? Yes, says Kazunari Shibata, an
astrophysicist from Kyoto University in Japan, and it could have
incredible consequences. At the recent Space Weather Workshop in
Boulder, Colo., sponsored by the National Science Foundation, the
National Oceanic and Atmospheric Administration (NOAA) and NASA, Shibata
gave a sobering presentation on the possibility of “superflares,” solar
flares that contain energy 1,000 times larger than what has been
observed in modern times.
Solar flares are a common type of solar
eruption, an explosive release of the magnetic energy concentrated in
sunspots. Flares are an everyday occurrence – small ones – and can range
in energy output over many orders of magnitude. The NOAA Space Weather
Scales classifies flares by peak X-ray output on a 1-5 scale (R1-R5),
with a flare rated “extreme” (R5) said to occur less than once a solar
cycle. In this current cycle, no flare has exceeded the strong (R3)
level. Solar flares are known to cause blackouts of radio communications
on the sunlit side of the Earth and disrupt radio navigation services.
They provide the energy for a class of energetic particle acceleration
that results in solar radiation storms that can disturb or damage
satellites. They are also sometimes associated with geomagnetic storms
that, if severe enough, can disturb the Earth’s electrical grid.
Shibata presented a statistical
analysis suggesting a superflare, off-the-charts of our current
classification system, should occur about once every 10,000 years. But
how do we know if the record of satellite observations of flare energy
go back only to the mid-1970s? The answer lies outside our solar system.
The NASA Kepler mission, launched in 2009, has been looking for
Earth-like planets orbiting other stars. Kepler has seen a lot of stars
and has shown, through further analysis, that many have properties
similar to our sun. In fact, scientists have observed over 80,000 such
stars. Hiroyuki Maehara and colleagues published a study (Nature, 2012)
that found — after painstakingly analyzing the Kepler observations over a
period of 120 days — evidence for 365 “superflares” on these stars.
These eruptions are thought to be physically similar to what our sun
produces, drawing the energy from the magnetic field in sunspots. –Washington Post
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