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Near the Edge

November 14, 2011

Early mariners feared that if they sailed too far, they’d fall off the edge of the Earth. Today, another mariner is about to reach the edge of the solar system. It won’t fall into a cosmic abyss, but it will enter a realm that’s never been explored before: the realm of interstellar space.

Voyager 1 has been sailing across the solar system for more than three decades. It cruised past the planets Jupiter and Saturn, then just kept on going. Today, it’s about 11 billion miles from the Sun.

That’s near the edge of the magnetic “bubble” that encloses the solar system. The bubble is generated by the Sun’s magnetic field and the flow of particles from its surface known as the solar wind.

Over the last few years, Voyager’s measurements showed that the solar wind was slowing down. By the summer of last year, the wind’s speed away from the Sun had slowed to zero, and it’s stayed at that same level — an indication that it’s being turned sideways by the winds of other stars.

This region forms a transition zone between the Sun’s region of magnetic influence and interstellar space. Voyager scientists expect the craft to finish crossing this region in the next couple of years. Once it does, it’ll leave behind the hot solar wind and enter a realm that’s dominated by other stars.

Voyager has enough power to study that region for a decade or so — giving us a good look at the universe beyond the edge of the solar system.


Script by Damond Benningfield, Copyright 2011


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