Voyager 1 nears edge of solar system
Washington - A spacecraft launched 33 years ago has nearly reached the edge of the solar system, travelling further than any other known human-made object, Nasa said Monday.
The Voyager 1 spacecraft, which launched September 5, 1977, has travelled some 17.4 billion kilometres from Earth and is now in an area of the solar system where the solar winds of particles blown off by the sun have slowed, signalling it will soon leave the solar system altogether.
Voyager 1 visited Jupiter and Saturn in 1979 and 1980, sending back the first detailed images of their moons, and along with sister craft Voyager 2 took images of all the outer planets. In 1990, Voyager took the first complete photo of the solar system.
It is now studying the heliosheath, which surrounds the outer edge of the solar system and where the sun's influence wanes.
Instruments aboard the craft show the solar wind slowed to zero in June, signalling the craft was near but not quite outside the solar system, scientists told a meeting of the American Geophysical Union in San Francisco.
The final exit from the solar system will happen in about four years, when Voyager I leaves the heliosheath and crosses into interstellar space. They believe that the transition will be signalled by a drop in the density of hot particles and an increase in cold particles.