Solar Cycle 24 Begins

Solar Cycle 24 Begins

http://science.nasa.gov/headlines/y2...larcycle24.htm

Jan. 10, 2008: Hang on to your cell phone, a new solar cycle has just
begun.

"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). [Larger image]
[Movie]

Solar activity waxes and wanes in 11-year cycles. Lately, we've been
experiencing the low ebb, "very few flares, sunspots, or activity of any
kind," says Hathaway. "Solar minimum is upon us."

The previous solar cycle, Solar Cycle 23, peaked in 2000-2002 with many
furious solar storms. That cycle decayed as usual to the present quiet
leaving solar physicists little to do other than wonder, when would the
next cycle begin?


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The answer is now.

"New solar cycles always begin with a high-latitude, reversed polarity
sunspot," explains Hathaway. "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 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.

Right: The first auroras of the new solar cycle, photographed Jan. 4,
2008, by Calvin Hall of Palmer, Alaska. [more]

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 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.

Every year, intercontinental flights carry thousands of passengers over
Earth’s poles. It's the shortest distance between, say, New York and
Tokyo or Beijing and Chicago. In 1999, United Airlines made just twelve
trips over the Arctic. By 2005, the number of flights had ballooned to
1,402. Other airlines report similar growth.

"Solar storms have a big effect on polar regions of our planet," says
Steve Hill of the Space Weather Prediction Center. "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 long way around."



Above: An increasing number of international business flights cross
Earth's Arctic to save time, fuel and money. [Larger image]

Now for the good news: More solar storms also means more auroras—"the
greatest show on Earth." During the last solar maximum, Northern Lights
were spotted as far south as Arizona, Florida and California. Not so
long ago, only visitors to the Arctic regularly enjoyed auroras, but
with increasing attention to space weather and constantly improving
forecasts, millions of people at all latitudes will know when to go out
and look.

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.