NASA's new Solar Dynamics Observatory may be getting all the press this week for its retina-searing first pictures of the sun. But two old sun-observing warhorses recently showed they're not quite ready for pasture yet.
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The twin, golf cart-size spacecraft of NASA's Solar Terrestrial Relations Observatory (STEREO) mission filmed, in ultraviolet light, the largest solar "prominence" in 15 years, according to the space agency. (See the video above, which compresses about 19 hours of solar activity on April 12 and 13).
Stretching nearly halfway across the sun, the looping eruption of ionized helium "is definitely one of the largest" solar prominences ever witnessed, said Madhulika Guhathakurta, a STEREO program scientist at NASA headquarters in Washington, D.C.


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