Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2000 March 9
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Sun Storm: A Coronal Mass Ejection
Credit: SOHO Consortium, ESA, NASA

Explanation: Late last month another erupting filament lifted off the active solar surface and blasted this enormous bubble of magnetic plasma into space. Direct light from the sun is blocked in this picture of the event with the sun's relative position and size indicated by a white half circle at bottom center. The field of view extends 2 million kilometers or more from the solar surface. While hints of these explosive events, called coronal mass ejections or CMEs, were discovered by spacecraft in the early 70s this dramatic image is part of a detailed record of this CME's development from the presently operating SOlar and Heliospheric Observatory (SOHO) spacecraft. Near the minimum of the solar activity cycle CMEs occur about once a week, but as we approach solar maximum rates of two or more per day are anticipated. Though this CME was clearly not headed for Earth, strong CMEs are seen to profoundly influence space weather, and those directed toward our planet and can have serious effects.

Tomorrow's picture: Sky and Planets

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.