Two main types of explosions occur on the sun: solar flares and
coronal mass ejections. Unlike the energy and X-rays produced in a solar
flare – which can reach Earth at the speed of light in eight minutes –
coronal mass ejections are giant clouds of solar material that take one
to three days to reach Earth. Once at Earth, these ejections, also
called CMEs, can impact satellites in space or interfere with radio
communications. During CME Week from Sept. 22 to 26, 2014, we explore
different aspects of these giant eruptions that surge out from our
closest star.
Three
NASA observatories work together to help scientists track the journey
of a massive coronal mass ejection, or CME, in July 2012. Image Credit: NASA/SDO/STEREO/ESA/SOHO/Wiessinger. Download video
On July 23, 2012, a massive cloud of solar material erupted off the sun's right side, zooming out into space. It soon passed one of NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft, which clocked the CME as traveling between 1,800 and 2,200 miles per second as it left the sun. This was the fastest CME ever observed by STEREO.
Two
other observatories – NASA's Solar Dynamics Observatory and the joint
European Space Agency/NASA Solar and Heliospheric Observatory --
witnessed the eruption as well. The July 2012 CME didn't move toward
Earth, but watching an unusually strong CME like this gives scientists
an opportunity to observe how these events originate and travel through
space.
STEREO's unique viewpoint from the sides of the sun combined with the
other two observatories watching from closer to Earth.Together they
helped scientists create models of the entire July 2012 event. They
learned that an earlier, smaller CME helped clear the path for the
larger event, thus contributing to its unusual speed.
Such data helps advance our understanding of what causes CMEs and
improves modeling of similar CMEs that could be Earth-directed.
Watch the movie to see how NASA's solar-observing missions worked together to track this CME.
Related Links
