NASA's Solar Dynamic Observatory captures "coronal rain," a beautiful and mysterious phenomenon on the Sun.

A modest solar flare erupted on July 19, 2012, followed by a coronal mass ejection, sending solar wind flying out into interplanetary space. Not all the plasma managed to escape, though, and what happened next is stunning. For a full 21 hours following the flare, plasma rained back down onto the Sun, following and lighting up the invisible lines of magnetic field that dance chaotically on the Sun's surface.

NASA's Solar Dynamic Observatory (SDO) captured the coronal rainfall in a 4-minute video, where every second of video corresponds to 6 minutes of real time. The SDO's Atmospheric Imaging Assembly (AIA) recorded extreme ultraviolet light at 304 Angstroms, showing ionized gas that's 90,000°F, almost 10 times hotter than the Sun's visible surface.

This isn't the first time SDO has studied the mysterious coronal rain, nor will it be the last. The transient phenomenon still isn't well understood — why, for example, does the rain fall so slowly? Beautifully detailed videos from SDO and its Sun-observing companions, such as Hinode, SOHO, and STEREO, will help solve these mysteries.


Image of Peter


February 25, 2013 at 6:30 pm

That video is a running faucet suspended in air. Too bad the camera saturates at the beginning to white-out.

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Image of Pete


February 26, 2013 at 6:31 pm

Good story, Monica.
Is the rain really falling slowly? By what measure? It appears to fall several earth-diameters in one second of the video. (They put an "earth" there for perspective.) If one second is six minutes in real time, and the "rain" travels at least 24,000-some miles in that period, I would tend to think it's falling pretty darned fast - like 4,000 miles per minute or 67 miles per second. Or is that really slow in solar terms?
Thanks for the great reporting.
Your fan,
Pete DeGraff
Niantic, CT

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