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NCAR Instruments Spot Major Coronal Mass Ejection

September 9, 2005

BOULDER — Researchers at the National Center for Atmospheric Research (NCAR) used specialized telescopes to capture these detailed images of an unusually energetic coronal mass ejection (CME) on September 7. Even though the storm was not aimed directly at Earth, the event led to a complete blackout of high frequency communications in North and South America, according to the NOAA Space Environment Center.

The CME moved through the corona at a speed of about 5.8 million miles per hour, making it the fastest such disturbance that NCAR’s High Altitude Observatory (HAO) has measured in more than 20 years of observations. NOAA’s Space Environment Center has warned that power grids, communications satellites, and navigation systems could be affected over the next two weeks.

To obtain these images, NCAR scientists used a pair of advanced instruments based at HAO's Mauna Loa Solar Observatory. The two top images were taken with a coronameter, known as the Mark IV, that records artificial eclipse images of the solar corona in visible light. These images reveal the density structure of the corona and show the coronal mass ejection emerging near the east limb, or left side, of the Sun (upper left image) and then erupting throughout much of the corona and into interplanetary space (upper right).

The lower two images were taken with NCAR’s Polarimeter for Inner Coronal Studies, which captures cooler structures. It shows the core of the mass ejection (also known as a prominence) at approximately the same time.

Animations: Click on each image to launch an animated loop of the event unfolding over time. For details about these animations, see the ACOS Daily Summary page.
Mark IVMARK IV
White-Light Coronagraph
PICSChromospheric Helium Imaging Photometer (CHIP)
CHIPPolarimeter for Inner Coronal Studies (PICS)

CMEs are dramatic events in the lower corona that release billions of tons of charged particles. If they are aimed toward Earth, they have the potential to produce severe geomagnetic storms, or space weather, which can affect satellite orbits and ground-based communications and power systems.

Prominences are huge clouds of cool gas that are often carried outward with CMEs, forming spectacular twisted arches as they move away from the Sun.

In addition to training a suite of advanced observation tools on the corona, NCAR scientists are creating computer models to better understand the underlying forces that lead to coronal mass ejections and other solar disturbances.

 Related sites on the World Wide Web 

MLSO Analysis Center - Daily Summary of ACOS data for September 7, 2005
NCAR High Altitude Observatory


The National Center for Atmospheric Research and UCAR Office of Programs are operated by UCAR under the sponsorship of the National Science Foundation and other agencies. Opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any of UCAR's sponsors.

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