NASA Satellites Capture Start of New Solar Cycle (Forwarded)

Jennifer Morcone
Marshall Space Flight Center, Huntsville, Ala. January 11, 2008
256-544-0034

Rob Gutro
Goddard Space Flight Center, Md.
301-286-4044

News release: 08-005

NASA Satellites Capture Start of New Solar Cycle

NASA scientists say a new solar cycle is beginning, and this could have
important repercussions for space-based technology ranging from GPS
navigation to weather satellites. On Jan. 4, a reversed-polarity sunspot
appeared, signaling the start of Solar Cycle 24. A sunspot is an area of
magnetic activity on the surface of the sun that appears as a dark spot on
its surface. Solar activity waxes and wanes in 11-year cycles and the
previous solar cycle, Solar Cycle 23, peaked in 2000-2002 with many
furious solar storms.

Lately, the sun has been experiencing very few flares, sunspots, or
activity of any kind -- a period of quiet called solar minimum. Now, the
sun's seasons are changing again. David Hathaway, solar physicist at
NASA's Marshall Space Flight Center in Huntsville, Ala., says, "New solar
cycles always begin with a high-latitude, reversed polarity sunspot."

"Reversed polarity" means a sunspot with opposite magnetic polarity
compared to sunspots from the previous solar cycle. "High-latitude" refers
to the sun's grid of latitude and longitude. Old cycle spots congregate
near the sun's equator. New cycle spots appear higher, around 25 or 30
degrees latitude.

The sunspot that appeared Jan. 4 fits both these criteria. It is high
latitude (30 degrees N) and magnetically reversed. The National Oceanic
and Atmospheric Administration (NOAA) has named the spot AR10,981, or
"sunspot 981" for short. Sunspot 981 was small -- only about as wide as
Earth, which counts as small on the grand scale of the sun -- and it has
already faded away. But its three-day appearance Jan. 4-6 was enough to
convince most solar physicists that Solar Cycle 24 is underway.

The onset of a new solar cycle is significant because of our increasingly
space-based technological society.

"Solar storms can disable satellites that we depend on for weather
forecasts and GPS navigation," says Hathaway. Radio bursts from solar
flares can directly interfere with cell phone reception while coronal mass
ejections (CMEs) hitting Earth can cause actual power outages.

Air travel can be affected, too. When airplanes fly over the poles during
solar storms, they can experience radio blackouts, navigation errors and
computer reboots all caused by space radiation. Avoiding the poles during
solar storms solves the problem, but it costs extra time, money and fuel
to take the longer route.

NASA is gearing up to study the active sun during Cycle 24 with the launch
of a new spacecraft, the Solar Dynamics Observatory. "SDO is a very
special observatory," says project scientist Dean Pesnell at NASA's
Goddard Space Flight Center, Greenbelt, Md. "Using a technique called
helioseismic imaging, the spacecraft will be able to look inside the sun
where solar activity begins. SDO will join SOHO, STEREO, Hinode and other
missions already in orbit to improve our understanding of solar storms and
lay the groundwork for better space weather forecasts."

"The beginning of the new solar cycle occurs just as the STEREO Mission is
completing its first year of operation," said Mike Kaiser, STEREO Project
Scientist at NASA Goddard. "The twin STEREO spacecraft are now 45 degrees
apart and are in good position to triangulate on solar activity from the
new cycle to provide better understanding of solar storms that can disrupt
our electronic lives. Ultimately, the research done by STEREO and other
solar missions will lead to more accurate predictions of when solar storms
will impact Earth."

"Intense solar activity won't begin immediately," notes Hathaway. "Solar
cycles usually take a few years to build from solar minimum (where we are
now) to Solar Max, expected in 2011 or 2012."

[NOTE: Images supporting this release are available at
http://www.nasa.gov/centers/marshall...tos08-005.html
]