Thursday, 29 March, 2001
Giant sunspot may explode
By BBC News Online science editor Dr David Whitehouse
Scientists are currently observing the largest sunspot seen on the
of our star for more than a decade.
Researchers think it could lead to a powerful flare some time in the
day or so. If this explosive event does occur, it will liberate in just
few seconds more energy than mankind has ever used.
The sunspot group, designated Noaa 9393, was first seen a month ago
was not nearly so large.
The Sun's rotation took it from view but when it reappeared a few days
astronomers were amazed that it had grown so big.
Over the past 24 hours it has become unstable displaying signs that its
pent-up energy is about to be explosively released.
The sunspot is a monster according to Joe Elrod of the US National
Observatory at Sacramento, California: "This is the first big one we
seen during this solar cycle," he told BBC News Online.
Every 11 years or so the Sun goes through a peak of activity when there
more sunspots on its surface. Solar observers say that 2001 is the year
the current peak.
Noaa 9393 is so large that it is even visible to the unaided eye,
astronomers say that under no circumstances should anyone without
protective equipment ever look towards the our star as blindness can
Sunspots are regions of the Sun's surface that are marginally cooler
their surroundings. They only appear dark by contrast. If they were
they would shine brighter than an arc lamp.
The 'big one'
They are caused when intense magnetic fields rise up from below the
visible surface. They then become twisted and distorted by surface
storing up vast amounts of magnetic energy.
Eventually, the magnetic energy becomes unstable and collapses,
the explosive heating of vast amounts of gas. This is when solar flares
The most intense solar flares are called "white light" flares and it is
type of event that sunspot group Noaa 9393 is expected to produce.
"We saw two small flares yesterday, and they may be the precursors to
big one," Joe Elrod said.
Scientists say that the Sun is currently going through a particularly
phase with many groups of sunspots on its surface.
NASA Science News for February 15, 2001
NASA scientists who monitor the Sun say that our star's awesome
magnetic field is flipping
a sure sign that solar maximum is here.
FULL STORY at