Interstellar winds change direction after 40 years

Particles from interstellar space which stream into our solar system, known as interstellar winds, have changed direction after 40 years.

Researchers examined data from 11 different spacecraft including Ulysses and the Interstellar Boundary Explorer (IBEX) for direct observation, and measurements of the flow of interstellar helium past the sun dating from the 1970s.

"This result is really stunning," says Dr. Dave McComas, IBEX principal investigator and study author. "Previously we thought the very local interstellar medium was very constant, but these results show just how dynamic the solar system's interaction is."

The new IBEX data shows that neutral interstellar atoms -- traveling at about 50,000 miles per hour -- are flowing into the solar system from a different direction that previously observed.

"We are finally able to resolve why these fundamental measurements have been changing with time: we are moving through a changing interstellar medium," said study co-author Nathan Schwadron.

"We think the change in wind direction could be explained by turbulence in the interstellar cloud around the Sun," said Dr. Priscilla Frisch, lead author and senior scientist in the Department of Astronomy and Astrophysics at the University of Chicago.

"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 researcher Eberhard Möbius.

"However, this finding may teach us about the dynamics at the edges of these clouds," Möbius said. "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."