24 solar cycle


"On January 4, 2008, a reversed-polarity sunspot appeared—and this signals the start of Solar Cycle 24," says David Hathaway of the Marshall Space Flight Center.

Above: Images of the first sunspot of Solar Cycle 24 taken by the NASA/ESA Solar and Heliospheric Observatory (SOHO).
The sunspot that appeared on January 4th fits both these criteria. It was high latitude (30 degrees N) and magnetically reversed. NOAA named the spot AR10981, 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 on Jan. 4-6 was enough to convince most solar physicists that Solar Cycle 24 is underway.
Doug Biesecker of NOAA's Space Weather Prediction Center in Boulder, Colorado, likens sunspot 981 "to the first robin of spring. There's still snow on the ground, but the seasons are changing." Last year, Biesecker chaired the Solar Cycle 24 Prediction Panel, an international group of experts from many universities and government agencies. "We predicted that Solar Cycle 24 would begin around March 2008 and it looks like we weren't far off," he says.
"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 electrical power outages. "The most famous example is the Quebec outage of 1989, which left some Canadians without power for as much as six days."
Air travel can be affected, too.
Strange but True: While Solar Cycle 24 has begun, Solar Cycle 23 has not ended. Both cycles will coexist for a period of time, perhaps a year or more, as one dies down and the other comes to life. In the months ahead we may see old-cycle sunspots and new-cycle sunspots on the sun at the same time.
Much of this is still years away. "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."
It's a slow journey, but we're on our way.

read the full article at science@nasa link is given below....
http://science.nasa.gov/headlines/y2008/10jan_solarcycle24.htm