August 28, 1998:
US Geological Survey officials have announced that
energetic particles from a large solar mass ejection began
impacting Earth's magnetic field
at about 3:00 am EST on Wednesday August 26. The eruption has triggered a
geomagnetic storm that could last for several days. It is difficult
to predict how severe the storm will become, but
it is possible that aurora could be seen over
the next few nights, even at mid-latitudes in the U.S.
A severe magnetic storm in March 1989
caused aurora that were reported as far south as Mexico.
Click for 24-hr forecasts of geomagnetic conditions |
NASA's Ultraviolet Imager satellite observed this aurora
over the North Pole last night at approximately 11:30 EST.
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Watch the Aurora Live from Space
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Solar flares and coronal mass ejections create
high-speed particles which cause auroras, known in the northern
hemisphere as Northern Lights. The image shown here
is a real-time satellite image of the Earth's auroral region above the
North Pole. From the ground auroras appear as shimmering curtains
of red and green light in the sky.
Particles from solar flares can also disrupt radio communication, and
the radiation from the flares can give passengers in airplanes a dose of
radiation equivalent to a medical X-ray. Sunspots may have a long-term
connection with the Earth's climate. Scientists are currently debating whether
ice ages on Earth are related to the Sun having fewer
sunspots than usual.
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Current Image of Earth's Aurora
Updated every 7 minutes.
Don't forget to hit RELOAD!
Click on the image to view a larger picture, and for more information about the
polar Ultraviolet Imager.
The image, above,
was made with NASA's Ultraviolet Imager,
a polar spacecraft whose main job is to take
ultraviolet pictures of the aurora. By
taking the pictures from space, rather than from
Earth, glare from the bright Sun is not a problem
and the aurora can be seen both on the
night and day side of the Earth. For more
information on aurora and the interpretation
of images like the one above, please visit
UVI Aurora Headquarters at
the NASA Marshall Space Sciences Lab.
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The current geomagnetic storm was triggered by a solar mass ejection
like the ones pictured right and below.
Coronal mass ejections, or "CME's", expand
away from the Sun at speeds as high as 2000 km per second.
They carry up to ten billion tons of charged particles away from the Sun.
Coronal mass ejections are not the same as solar flares. It was
once thought
that CMEs were caused by flares, but now it is understood that they
are not associated. In space CMEs typically create shock waves that
produce energetic
particles which can damage both electronic equipment
and astronauts that venture outside
the protection of the Earth's magnetic field. Solar flares,
on the other hand, directly affect the
ionosphere and radio
communications at the Earth, and also release energetic particles into
space.
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The image above, when clicked, shows a sequence of four images taken by the LASCO C2 coronagraph
aboard SOHO of a coronal mass ejection that occurred on 1997 April 7.
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A solar mass ejection observed in October 1989. The image was adapted
from data in the High Altitude Observatory/Solar Maximum Mission archives.
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A series of solar X-ray events have been reported by
NOAA's Space Environment Center since August 19th, culminating in the
recent eruption.
However, this may be just the beginning. The number of
geomagnetic storms increases and decreases with the
solar cycle, and the next solar
maximum is less than two years away. Experts predict that
the peak of the current sunspot cycle will be bigger
than average and that the maximum should occur sometime in
2000 AD, a good year for "space weather."
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Author: Tony Phillips
Curator: Bryan Walls
NASA Official: John M. Horack
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