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At 2:50 Universal Time,

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on July 23, 2012, the sun unleashed

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an incredibly powerful coronal mass ejection, or

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CME. A CME is a huge cloud of plasma

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that bursts out of the sun's atmosphere and is held together with magnetic fields.

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An average CME travels at about 1 million miles

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per hour, and weighs around 2 trillion tons.

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On this particular Monday, however, the sun unleashed a perfect

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storm of plasma. Thanks to NASA's far-ranging

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heliophysics fleet, we have an excellent picture of the event.

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The incredibly high-resolution view of the sun,

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provided by NASA's Solar Dynamics Observatory, or SDO,

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revealed the beginning of the eruption in several different wavelengths of ultraviolet

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light. [Music]

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NASA's twin STEREO spacecraft, orbiting the sun ahead and behind

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Earth, gave a similar view from alternate perspectives.

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The STEREO satellites also carry coronagraphs, which block the bright

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solar disk, to make the fainter extended solar atmosphere, or corona,

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visible. As a result, they were able

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to image the actual CME as it left the sun.

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The CME headed in the direction of the STEREO A spacecraft

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at an astonishing 6.7 million miles an hour.

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As the CME arrived at

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STEREO A, the coronagraph and STEREO's wider-field

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heliospheric imagers were pummeled by high-energy particles,

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which appear like snow in the imagery. The joint ESA

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and NASA Solar and Heliospheric Observatory, or SOHO,

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that has been observing the sun since 1995,

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captured footage of the CME in both of its coronagraphs, which overlap

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their fields of view. All of these

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data allow computer models to reconstruct the full shape and

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expansion of the CME. The main event is preceded by

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a few smaller CMES, one of which was Earth-directed.

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It is immediately clear how much larger and faster

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the July 23rd CME was, as it blasted towards

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STEREO A. NASA's fleet of heliophysics

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spacecraft, watching the sun from all sides, improves our understanding,

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and enables predictions of these solar outbursts.

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[Music] [Beeping]

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