NASA Sees Far Side of the Sun
NASA's twin STEREO
spacecraft are offering the first glimpse of the far side of the sun, the space
agency announced today.
The two spacecraft,
launched Oct. 25, 2006, are beaming back over-the-horizon images "that
have researchers and forecasters glued to their monitors," according to a
statement.
"This is a perspective
we've never had before," says STEREO mission scientist Lika Guhathakurta
of NASA headquarters. "We're now monitoring more than 270 degrees of solar
longitude - that's 3/4ths of the star."
Just in time
Because the sun rotates,
all of it is seen from Earth over time. But at any given time, only half of the
star is visible. Scientists who monitor
solar eruptions and the space storms they hurl toward Earth are eager to
monitor the whole star 24/7. Seeing storms on the far side, which is of course
just as bright and active as the near side, would improve forecasting
abilities.
"After all these years,"
Guhathakurta quipped, "we're finally getting to see the dark side of the
sun."
Since the two STEREO
spacecraft went into orbit around the sun at the beginning of 2007, they have
been slowly drifting apart from Earth, and from each other. They are now 90
degrees apart. They will be in their final positions on Feb. 6, 2011, hovering
180 degrees apart and imaging the entire sun all the time. That timing will
match with the next expected peak in solar activity.
The sun is at a low point
in it's 11-year cycle of activity now. But over the next few years, sunspots
will become more common and flares
more frequent. The peak will likely occur in 2012.
Dangerous solar storms can
happen anytime, however. A major one, thought to occur every 100 years or so,
could debilitate communication and power systems on Earth, according to a
National Academy of Sciences report
earlier this month.
Already better
Because of the way the sun
spins, STEREO-B gets a sneak preview of sunspots and coronal holes before they
rotate around and face Earth.
"I know forecasters at
NOAA's Space Weather Prediction Center monitor STEREO-B very closely,"
said Chris St. Cyr of the Goddard Space Flight Center. "It lets them know
what's coming."
Already, STEREO-B enjoys a
3-day look-ahead advantage over Earth-based observatories.
No images were released
today. However, the probes are equipped with sensors that measure the speed,
direction and composition of the solar wind; receivers that pick up radio
emissions from explosions and shock waves in the sun's atmosphere; telescopes
that image the solar surface and all the tempests that rage there; and coronagraphs
to monitor events in the sun's outer atmosphere.
"So, really,"
says Guhathakurta, "we're not only seeing the sun's dark side, we're
feeling, tasting and listening to it as well."
- Gallery:
Solar Storms
- Video
- Space Storm Warning
- Perfect
Space Storm Could be Catastrophic on Earth, Study Concludes









