NASA's Interstellar Boundary Explorer (IBEX) spacecraft recently detected a mysterious ribbon of particles at the edge of the solar system. Scientists now say it may have been formed by atoms reflected back into the solar system by the Milky Way's magnetic field.
A ribbon in the sky? Who, besides Stevie Wonder, knew?
Until last October, no one knew. Then NASA's Interstellar Boundary Explorer (IBEX) spacecraft revealed the unexpected feature as it mapped the frontier between the solar system and interstellar space.
Now, a team of space physicists posits that the ribbon seen in the IBEX map of the sky is likely being formed by atoms that originally came from the sun as part of the solar wind. The Milky Way's magnetic field is in effect reflecting them back in a kind of cosmic bank shot.
If the explanation holds up, IBEX's ribbon represents the first crude measurement of the local portion of the galaxy's magnetic field, says Jacob Heerikhuisen, a space physicist at the University of Alabama at Huntsville, who led the team.
"That's the most exciting thing for us," he says.
Researchers are trying to understand the boundary region between the solar system and interstellar space because that boundary shields the solar system from some 90 percent of the high-energy cosmic rays bombarding it, explains Nathan Schwadron, a space physicist at Boston University and member of the team reporting the results in the Jan. 10 issue of the Astrophysical Journal Letters.