The Sun Flies Like a Bullet

The Milky Way's magnetic field constantly buffets our little star.

By Jennifer Barone|Tuesday, August 07, 2007
A magnetic field (cylindrical strings) distorts our solar system.
Image courtesy of M. Opher et al.

Our solar system, which careers around our galaxy’s center at nearly half a million miles per hour, isn’t round. It isn’t even symmetrical. Instead, says George Mason University astrophysicist Merav Opher, the sun’s domain is shaped like a slightly squashed bullet and tilts up to 90 degrees away from the plane of the magnetic field of the rest of the Milky Way.

Opher got her results by working with particle and radio-wave data from the two Voyager probes, which are now more than 100 times as far from Earth as we are from the sun, near a boundary known as the termination shock. There, the barrage of particles blasting out from the sun—the solar wind—is slowed by our motion through the galaxy. Using the Voyager data, researchers can now monitor the magnetic field at the edge of our solar system. “Even though the local interstellar field is kind of weak, it really distorts the shape of our solar system,” Opher says. “Because of our motion through the galaxy, we have a bullet shape, like a boat going through the ocean. But the magnetic field takes our bullet shape and tilts it. This is a huge effect; we’re really inclined.”

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