The New Year got off to a striking start for scientists at SOHO’s
operations centre who were treated to a dazzling display from the Sun on
4 January. Images of an unusually beautiful ejection of solar material
were captured by several instruments on the ESA-NASA spacecraft.

In the early hours of 4 January, another spectacular Coronal Mass
Ejection (CME) took off from the Sun. The CME, a ball of ionized gas at
about one million degrees Celsius hurled from the outer atmosphere of
the Sun, began as a filament eruption seen by the Extreme ultraviolet
Imaging Telescope (EIT).

As it sped through space at more than 900 kilometres per second, the
Large Angle and Spectrometric Coronagraph (LASCO) instrument tracked
its progress. The complexity and structure of this CME which was
visible as it passed through the LASCO fields of view amazed even
experienced solar physicists at the SOHO operations center.

Although the centre of this particular CME was directed almost a full
90 degrees away from the Sun-Earth connection line, it still appeared
as a (weak) full halo event, opening up the possibility of a small
impact on Earth’s space weather. Typically, a CME can often cause
fantastic aurorae which are visible a few days after the ejection
from the Sun. (It takes a few days for the hot gas to traverse the
150 million kilometres between the Sun and Earth.)

SOHO plays an important role as a space-weather watchdog. It is the
only spacecraft which can see these CMEs and can tell if they are
directed towards Earth. Satellite operations, radio communications
and power grids can all be affected by large CMEs, and advance
warning of these events allows preventative measures to be taken.

USEFUL LINKS FOR THIS STORY

* More about SOHO
http://sci.esa.int/soho/
* SOHO hotshots
http://sohowww.estec.esa.nl/hotshots/
* What is a Coronal Mass Ejection?
http://soho.nascom.nasa.gov/explore/faq/cme.html#

IMAGE CAPTION: (1.9MB)
[http://sci.esa.int/content/searchimage/searchresult.cfm?aid=14&cid=12&oid=29200
&ooid=29202]
Another spectacular Coronal Mass Ejection (CME) took off from the Sun
in the early hours of January 4, starting off as a filament eruption
seen by the Extreme ultraviolet Imaging Telescope (EIT) in the 195 A
images. The complexity and structure of the CME as it passed through
the Large Angle and Spectrometric Coronagraph (LASCO) C2 and C3 fields
of view amazed even experienced solar physicists at the SOHO operations
center.