Although the ribbon looks bright in the IBEX map, it does not glow in any conventional sense. The ribbon is not a source of light, but rather a source of particles–energetic neutral atoms or ENAs. IBEX’s sensors can detect these particles, which are produced in the outer heliosphere where the solar wind begins to slow down and mix with interstellar matter from outside the solar system. “This ribbon winds between the two Voyager spacecraft and was not observed by either of them,” notes Eric Christian, IBEX deputy mission scientist at NASA’s Goddard Space Flight Center. “It’s like having two weather stations, but missing the big storm that runs between them.” (via NASA -Giant Ribbon Discovered at the Edge of the Solar System
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The Committee to Nuke Elysium 