spacetoday.net: Voyagers discover solar system "squashed"

Posted: Tue, Dec 11, 2007, 7:40 AM ET (1240 GMT)
Voyagers at heliosheath illustration (NASA/JPL)

NASA's twin Voyager spacecraft have revealed that the solar system in "squashed" relative to the interstellar medium, scientists said Monday. Voyager 2 cross into a region called the heliosheath, the region where the solar wind runs up against the interstellar medium, about 1.5 billion kilometers closer to the Sun than Voyager 1, which reached the heliosheath in late 2004. Because the two spacecraft are headed away from the Sun in different directions, scientists concluded that the bubble carved into the interstellar medium by the solar wind is not perfectly spherical. Scientists got more information from this mission than Voyager 1 because Voyager 2's plasma science instrument is still working, and managed to capture data as the termination shock at the heliosheath "sloshed" back and forth, allowing the spacecraft to sample it several times.