Solar System Angling From Milky Way

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May 11, 2007 — Our solar system is taking the road less traveled from the rest of the Milky Way galaxy, say scientists who used radio signals from two spacecraft nearing interstellar space to map the unexpected route.

The researchers determined that the magnetic field in interstellar space is propelling our solar system along at a 60-degree to 90-degree angle from the rest of the galaxy.

That's happening because the part of the interstellar magnetic field that comes closest to our system is not parallel to the spiraling arms of the galaxy, as it appears to be elsewhere.

As a result, our solar system has taken on a bullet-shaped appearance as it soars through space, say Merav Opher, with George Mason University in Fairfax, Va., who published his research in this week's issue of the journal Science.

The researchers used data from the two 30-year-old Voyager probes and computer modeling to calculate the solar system's position.

To measure our solar system, scientists study the places where the sun's influence ends and interstellar space begins, an area known as the heliosphere.

The sun's domain is flecked with ionized particles called the solar wind, which surrounds the system like a bubble. Beyond the bubble is interstellar space, which contains mostly hydrogen and helium.

Researchers modeled the area where the heliosphere runs into the interstellar magnetic field and beyond to find the odd angle.

Studying the interaction between the heliosphere and interstellar space yields insights into phenomena that can affect Earth, such as galactic cosmic rays, points out Randy Jokipii, with the University of Arizona in Tucson, in a related paper.

Voyager 1 has passed through the outer bubble of solar wind is now exploring a transition region known as the heliosheath. Voyager 2 has yet to pass through the solar wind termination zone.

Additional studies are planned using both probes as well as the Solar and Heliospheric Observatory, and a new spacecraft called the Interstellar Boundary Explorer, is scheduled to launch next year.