An angry Sun fired off another powerful X-class flare
Tuesday, April 10. X-class flares are the most powerful
classification, and this flare, rated X-2, was the most
recent in a series that included one of the most powerful
solar blasts in 25 years.

An eruption of electrified gas, called a Coronal Mass
Ejection, or CME, was observed shortly after Tuesday’s flare,
and it is heading our way. Depending on the orientation of
the magnetic field carried by the CME cloud, it may cause a
magnetic storm when it impacts the Earth’s own magnetic
field.

Tuesday’s flare which was observed by the Solar and
Heliospheric Observatory (SOHO) and NASA’s Transition Region
and Coronal Explorer (TRACE) occurred at 1:25 a.m. EDT and
came from a region on the Sun designated active region 9415.
This region is rotating with the Sun and currently points
towards Earth. Active region 9415 includes a sunspot group
and has generated three X-class flares this month, including
an X-5 flare on April 6.

The front of the ejection cloud associated with Tuesday’s
flare hit Earth shortly after
9 a.m. EDT today. Moderate to strong storm levels, rated G2 –
G3, will be possible during today and tomorrow as the CME
passes Earth, according to the National Oceanic and
Atmospheric Administration’s Space Environment Center (NOAA
SEC), Boulder, CO.

“This is another in an exciting series of solar events during
this maximum epoch of the current solar activity cycle,” said
Dr. Ernest Hildner, Director of the NOAA SEC. The NOAA SEC
classifies flares according to their power and estimates,
tracks, and evaluates the effects of solar activity on the
space environment near Earth. The NOAA SEC is the federal
agency responsible for making official space weather
predictions.

Solar flares, among the solar system’s mightiest eruptions,
are tremendous explosions in the atmosphere of the Sun,
capable of releasing as much energy as a billion megatons of
TNT. Caused by the sudden release of magnetic energy, in just
a few seconds flares can accelerate solar particles to very
high velocities – almost to the speed of light – and heat
solar material to tens of millions of degrees.

CME eruptions, often associated with flares, are clouds of
electrified, magnetic gas weighing billions of tons ejected
from the Sun and hurled into space with speeds ranging from
12 to 1,250 miles per second. The CME associated with
Tuesday’s flare was thrown from the Sun at an estimated 1,000
miles per second. CMEs can be even more powerful than flares
and the total energy in a good-sized ejection is about 100
times greater than that of the largest flares.

Depending on the orientation of the magnetic fields carried
by the CME cloud, Earth-directed ejections can cause magnetic
storms by interacting with the Earth’s magnetic field,
distorting its shape and accelerating electrically charged
particles, electrons and atomic nuclei, trapped within.
Severe solar weather is often heralded by dramatic auroral
displays but the magnetic storms can also affect satellites,
radio communications and power systems.

Active region 9415 is expected to produce more solar
outbursts because it has a complex magnetic field structure.
Active regions are areas near the Sun’s visible surface where
a concentration of distorted magnetic fields exists. Sunspots
are often found in active regions because the strong magnetic
fields there slow the flow of heat from the Sun’s interior,
keeping part of the region slightly cooler than its
surroundings, which causes it to appear as a dark spot on the
solar surface.

The SOHO project is an international cooperative program
between NASA and the European Space Agency in the framework
of the International Solar Terrestrial Science Program.
Images of and additional information on the recent stormy
solar activity, including this flare, are available on the
Internet at:

  • http://sohowww.nascom.nasa.gov/
  • http://www.gsfc.nasa.gov/GSFC/SpaceSci/sunearth/sohox2flare/s
    ohox2flare.htm

  • http://www.sec.noaa.gov/SWN/