10 December 2007

An Oblong Solar System? Voyager2 Meets the Termination Shock Closer to Sun than Voyager 1

Voyager 2 met the edges of the heliopause 1 billion miles closer to the sun than did Voyager 1. That demonstrates an "oblongness" of the solar system caused by a compression effect from the interstellar "medium."
Because Voyager 2 crossed the heliosheath boundary, called the solar wind termination shock, about 10 billion miles away from Voyager 1 and almost a billion miles closer to the sun, it confirmed that our solar system is “squashed” or “dented”– that the bubble carved into interstellar space by the solar wind is not perfectly round. Where Voyager 2 made its crossing, the bubble is pushed in closer to the sun by the local interstellar magnetic field.

“Voyager 2 continues its journey of discovery, crossing the termination shock multiple times as it entered the outermost layer of the giant heliospheric bubble surrounding the Sun and joined Voyager 1 in the last leg of the race to interstellar space.” said Voyager Project Scientist Dr. Edward Stone of the California Institute of Technology, Pasadena, Calif.

The solar wind is a thin gas of electrically charged particles (plasma) blown into space by the sun. The solar wind blows in all directions, carving a bubble into interstellar space that extends past the orbit of Pluto. This bubble is called the heliosphere, and Voyager 1 was the first spacecraft to explore its outer layer, when it crossed into the heliosheath in December 2004. As Voyager 1 made this historic passage, it encountered the shock wave that surrounds our solar system called the solar wind termination shock, where the solar wind is abruptly slowed by pressure from the gas and magnetic field in interstellar spac
The ability to explore the very boundaries of the solar system is exciting for scientists at NASA's JPL. We are just beginning to understand some of the basic mechanisms of how the sun generates the solar wind, and the effect the solar wind has on the planets and the region of space surrounding the solar system.

Parts of the solar wind travel away from the sun at velocities above 1 million miles per hour. A solar sail that could tap into such swift winds could serve our early explorations of the solar system in the same way that canvas sails served the early exploration of earth's seas and oceans.

The sun throws enormous energies into local space, with Earth's atmosphere and magnetosphere interacting with a portion of that. At this time, very little is known of the sun's effect on Earth's weather and climate. But it makes sense to pay attention to the sun--to try to find out more about its part in our story.


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