Solar System Is "Bullet Shaped"


May 10, 2007

A graphic depicts the solar system, encased in an envelope of charged particles (yellow), as it passes through the interstellar magnetic field of the Milky Way galaxy (brown lines). A new study using data from the far-flung Voyager spacecraft found that the solar system takes on a bulletlike shape as it passes through space.

Our solar system flies through space in the shape of a speeding bullet, according to data from NASA's two Voyager spacecraft.

The sun and its planets are known to streak through the void of space at approximately 62,000 miles (100,000 kilometers) an hour.

The system travels within a bubble of solar wind—made of charged particles from the sun—called the heliosphere.

The edge of this bubble collides with the Milky Way galaxy's magnetic field at a distance some 200 times farther from the sun than Earth is.

A research team led by Merav Opher at Virginia's George Mason University found that, just outside the solar system, this interstellar magnetic field is inclined at a 60-degree angle relative to the plane of the Milky Way.

The solar system takes on its streamlined shape as it strikes the magnetic field at this angle, Opher explained.

"The shape of the solar system, this bullet, is really shaped by what lies ahead of us—the interstellar magnetic field," Opher said.

"The [prevailing] idea is that the environment just outside our solar system is patchy and turbulent," she added.

"There are lots of stars exploding and dying outside our solar system."

Opher and colleagues made the find using radio data from the veteran Voyager spacecraft. Though they have plied the skies since the 1970s, the craft only recently reached the solar system's edge.