BartSimpson wrote:
I hate reporters. Can't even bother with fact checking on this to find out that Pioneer 10 was the first man-made craft to depart the solar system, not this Johnny-come-lately.
Pioneer 10 is less than 100 AU from the Sun, and is moving at comparably slower speeds than both of the Voyager probes. Pioneer 11 was moving even more slowly, and is only around 80 AU from the sun currently. It doesn't really matter for us on Earth at this point, since we've lost all contact with both probes for essentially a decade now -- Pioneer 11 in 1997, and Pioneer 10 in 2003 (which was at best a weak signal).
In fact, the Pioneer probes have not been the farthest thing out here since 1998 (69 AU from the sun) -- both Voyager probes are moving at much higher speeds and, unlike their cousins in the Pioneer line, continue to function and will keep sending back information for years to come, most importantly information on the Heliopause, and the Heliopause which it has been studying for a few years now. To compare distances, Voyager 1 is currently around 120 AU from our star, and Voyager 2 is 93 AU away, and will likely pass Pioneer 10 before reaching the heliopause.
Voyager 2 and, possibly, Pioneer 10 have encountered the Heliosheath (it is significantly different in different directions as we discovered from Voyager 2, so we can't be sure), but only Voyager 2 is able to report on it from those two probes. Remember that our solar system also does not end where the planets end -- for example, Eris, part of our solar system and significantly larger than Pluto, is almost 100 AU from the sun.
As a final point, the lines which define where the solar system ends and does not is not specifically defined. It could be the heliopause, which we are just now closing on our first encounter for with Voyager 1. It could be the outermost orbit of Sedna, which is over 500 AU away at its farthest point (but significantly within the heliopause at other times). Or it could be the Oort cloud, a theoretical field of astronomical debris 50000 to 100000 AU away, the approximate edge of our sun being the dominant gravitational influence. Hence, this article is correct since it is following how scientists have been describing it as the edge.
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