A strange interstellar wind blows through our solar system

Interstellar winds appear to have changed direction, and scientists aren't certain why.
Interstellar winds appear to have changed direction, and scientists aren’t certain why.
(NASA/Goddard/Adler/University of Chicago/Wesleyan University)

When it comes to studying the region of interstellar space just beyond our solar system, nothing seems to work quite the way scientists imagined.

Take Voyager 1 for example. The spacecraft has confounded and delighted researchers for several years with unexpected observations of magnetic field and cosmic ray activity at the gateway to interstellar space.

Indeed, scientists disagree over whether Voyager 1 is still in the solar system.

Now, new research published in the journal Science suggests that the interstellar winds that gust through our heliosphere -- the vast bubble of magnetism that surrounds the sun and planets -- has changed direction over the last 40 years.


After comparing data gathered by 11 spacecraft between 1972 and 2011, researchers concluded that interstellar winds have changed direction by 4 to 9 degrees, upending long-held beliefs that the gusts were eternally steady.

“This result is really stunning,” said Dave McComas, study coauthor and principal investigator for NASA’s Interstellar Boundary Explorer, or IBEX, spacecraft.

“Previously we thought the very local interstellar medium was very constant, but these results show just how dynamic the solar system’s interaction is,” McComas said in a statement.

Our heliosphere, which is inflated like a balloon by the sun’s solar winds, deflects powerful cosmic rays, much the way the earth’s magnetic field shields us from much of the sun’s radiation.

But the heliosphere doesn’t block everything. Certain uncharged particles from interstellar space, such helium atoms, can enter and be tracked by spacecraft.

The heliosphere is currently moving through a vast interstellar cloud that is formally called the “local interstellar cloud” but has also been dubbed the “local fluff.”

The heliosphere is currently at the inside edge of the cloud, which is moving in a different direction. The two are moving past each other at a speed of 50,000 miles per hour, and it’s this motion that results in interstellar atoms “blowing” through the heliosphere and past earth.

It remains unclear to scientists exactly why the interstellar wind would change direction.


“it was very surprising to find that changes in the interstellar flow show up on such short time scales because interstellar clouds are astronomically large,” said study coauthor Eberhard Mobius, a University of New Hampshire physics professor and principal scientist for the IBEX mission.

“This finding may teach us about the dynamics at the edges of these clouds,” Mobius said in a statement. “While clouds in the sky may drift along slowly, the edges often are quite fuzzy and dynamic. What we see could be the expression of such behavior.”