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NASA’s IBEX finds mysterious ribbon at edge of solar system

The ribbon could be the solar system’s version of Earth’s northern and southern lights. The results of the discovery, made by NASA’s IBEX satellite, appear Friday in the journal Science.

In this computer generated image from NASA, the orange gas represents the interstellar medium. The bow shock is created because the heliosphere is moving through like a boat through the water, crashing through the interstellar gases.


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Astronomers have discovered what could turn out to be the solar system's version of Earth's aurora.

The phenomenon appears as a vast, mysterious ribbon at the edge of the solar system – the boundary between a giant bubble of charged particles that the sun blasts in all directions and the clouds of gas and magnetic fields that are found in interstellar space.

The ribbon shows up in a new, all-sky map of this boundary region produced by NASA's Interstellar Boundary Explorer (IBEX) satellite, which was launched last October. On Thursday, the National Aeronautics and Space Administration announced the discovery. The results appear in a collection of six papers in Friday’s edition of the journal Science.

The discovery of this ribbon feature "is a shocking new result for us," says David McComas, the lead scientist on the IBEX project.

Researchers are at a loss – at least for now – for an explanation. But some suggest that it could be the solar system's version of the northern and southern lights. Instead of appearing as a curtain of light, as Earth's auroras do, the solar system's version appears as a curtain of neutral particles.

Some of these neutral particles arrive from interstellar space. Others begin as charged particles that accelerate back toward the sun from the boundary between interstellar space and the sun's bubble, or heliosphere. Along the way, they pick up any electrons they need to become neutral atoms.

Current theories had suggested that IBEX might see small variations in the number of these neutral atoms in any one patch of space. But the ribbon represents an unexpected structure, and it registers upwards of three times the number of neutral atoms that theories had predicted.

One explanation for the ribbon: It’s appearing where the galaxy's magnetic-field lines are coming into contact with the heliosphere. Dr. McComas likens it to a ball moving inside a loose bundle of bungee cords.


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