Interstellar Wind Changes Direction After 40 Years: The Location of Our Solar System

Particles, known as interstellar winds, stream into our solar system from interstellar space. These winds flow in one direction, telling scientists a bit more about where we're located in the universe. Now, though, NASA has discovered that these particles have shifted direction over the past 40 years. The findings could tell researchers a little bit more about our place in the universe.

Researchers first noticed this change in the winds by examining data that spanned four decades. This data was collected from 11 different spacecraft, including IBEX, the Interstellar Boundary Explorer. The data from IBEX in particular showed that neutral interstellar atoms are flowing into the solar system from a different direction than previously observed. Interstellar atoms flow past the Earth as the interstellar cloud surrounding the solar system passes the sun at about 50,000 miles per hour.

"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 Eberhard Mobius, one of the researchers, in a news release. "However, this finding may teach us about the dynamics at the edges of these clouds--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."

The various sets of observations relied on three different methods to measure the incoming stellar wind. IBEX and another spacecraft, Ulysses, directly measured neutral helium atoms as they moved through the inner solar system. While IBEX's measurements are close to Earth, Ulysses' measurements were taken between 1.3 and 2 times further from the sun.

"Prior to this study, we were struggling to understand why our current measurements from IBEX differed from those of the past," said Nathan Schwadron, co-author of the new paper, in a news release. "We are finally able to resolve why these fundamental measurements have been changing with time: we are moving through a changing interstellar medium."

The new research reveals a little bit more about our solar system. It's important to know which way this interstellar wind flows, since it can help us understand our place in the cosmos through the vast sweep of time--where we've come from, where we're currently located and where we're going through our journey through the galaxy.

The findings are published in the journal Science.