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Voyager 2 Detects Peculiar Solar System Edge
ClickOnThis writes "CNN reports that Voyager 2 has detected evidence of the magnetic edge of the solar system (aka the heliopause) at 76 AU (1 AU = 93 million miles), much closer to the Sun than the location of 85 AU found by Voyager 1. From the article: 'This implies that the heliosphere, a spherical bubble of charged low-energy particles created by our Sun's solar wind, is irregularly shaped, bulging in the northern hemisphere and pressed inward in the south. [...] The researchers think that the heliosphere's asymmetry might be due to a weak interstellar magnetic field pressing inward on the southern hemisphere.'"
The 2 data points aren't informing the size or shape, but are observations related to a theory.
The theoretical belief is that it should be relatively uniform, but it does not appear to be. Are 2 observations sufficient? No, but a difference in 9 AU in the 2 observations is significant in that it is far off the scall were it less than 1, or maybe only slightly different, that would better confirm the theory. If the physics say that it ought to be uniform, and observations shows that it isn't, th theory needs to be adjusted.
Could it not simply mean that it changes in size? I'd be surprised if it *didn't* change in size, based on all the variable energy in the solar system. The sun changes, the planets change place, etc.
What variability? The sun is pretty constant on short time scales. The sun is being observed in detail by other spacecraft specifically designed for that task, like Helios. These spacecraft directly measure the solar wind and track the effects of solar. I'm sure the people at NASA have included that data into their analysis. They are rocket scientists, after all. The planets exert essentially zero influence over the heliosphere. So it's not like they have no idea about what's going without the Voyager data.
In theory, there's no difference between theory and practice. In practice, there is.