A new discovery that the particles streaming into the solar system from interstellar space have likely changed direction over the last 40 years helps scientists map our location within the Milky Way galaxy. The finding is crucial for understanding 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 in our journey through the galaxy. New data from the IBEX spacecraft show 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 23 kilometers per second (50,000 miles per hour).
Additionally, scientists now gain deeper insight into the dynamic nature of the interstellar winds, which has major implications on the size, structure, and nature of our sun’s heliosphere—the gigantic bubble that surrounds our solar system and helps shield us from dangerous incoming galactic radiation.
"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," says Eberhard Möbius, UNH principal scientist for the IBEX mission and co-author on the Science paper. Adds Möbius, "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."
"Prior to this study, we were struggling to understand why our current measurements from IBEX differed from those of the past," says co-author Nathan Schwadron, lead scientist for the IBEX Science Operations Center at UNH. "We are finally able to resolve why these fundamental measurements have been changing with time: we are moving through a changing interstellar medium."
Read: The paper, “Decades-long Changes of the Interstellar Wind Through our Solar System,”
The Daily Galaxy via University of New Hampshire