Friday, November 7, 2003
Aging Voyager reaches at the edge of solar system
Associated Press Los Angeles, November 6
The Voyager 1 spacecraft, the most distant human-made object, has reached the end - or perhaps just the beginning of the end - of our solar system, scientists argue in two new studies.
As of on Wednesday, 26 years after its launch, NASA's Voyager 1 was 13.5 billion kilometres from the sun. That's 90 times the distance separating the Earth from the sun.
As the robotic spacecraft continues to push far beyond the reach of the nine planets, two teams of scientists disagree whether it passed into the uncharted region of space where the sun's sphere of influence begins to wane.
The sun sends out a stream of highly charged particles, called the solar wind, that carves out a vast bubble around the solar system.
Beyond the bubble's ever-shifting boundary, called the termination shock, lies a region where particles cast off by dying stars begin to hold sway. That region, called the heliopause, marks the beginning of interstellar space and the end of our solar system. Whether Voyager 1 reached that mark or is still on approach remains unclear, with scientists providing evidence for both claims. Details appear today in the journal Nature.
"Neither explanation is certain," writes Len Fisk, of the University of Michigan, in an editorial accompanying the two studies.
© Hindustan Times Ltd. 2003.