About 12 billion miles from Earth, a boundary marks the edge of the sun and the beginning of interstellar space. When NASA's Voyager 2 space probe crossed that line more than 40 years after its launch, it returned a faint signal from deep space scientists now decoded.
Scientists at the University of Iowa have confirmed Voyager 2's transition to interstellar environment (ISM) by marking a peculiar jump in plasma density detected by a plasma wave instrument.
This increase in plasma density is evidence of the passage of Voyager 2 from the lower solar-typical plasma of hot wind to the cooler plasma of greater interstellar space.
The results echo the surge in plasma density experienced by Voyager 1
Don Gurnett, of the University of Iowa, corresponding author of the study, says: "Historically, the old idea that the solar wind will just gradually be extinguished as you go further into interstellar space is simply not true.
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However, they have moved to the ISM at similar distances from the Sun.
This provides valuable information on the structure of the heliosphere, the balloon created by the solar wind, and extends to the boundary of the solar system.
Dr. Bill Kurt, a scientist at the University of Iowa and co-author of the study, says, "This means that the heliosphere is symmetrical, at least at the two points where the Voyager
" is saying that these two points on the surface are almost at the same distance. "
The data from Voyager 2's Iowa Instrument also provides further guidance on the thickness of the heliosk, the outer region of the heliosphere, and the point at which the solar wind accumulates against the approaching wind in the interstellar effect of snowman on a city street Prof. Garnet.
Iowa scientists claim that the heliosphere varied with thickness ss, based on data showing that Voyager 1 sailed 10 AU farther from its twin to reach heliopause.
Some researchers have predicted that Voyager 2 will make this intersection first, based on heliosphere models.
Dr. Kurth added, "It's like looking at an elephant with a microscope.
"Two people go to an elephant with a microscope and make two different measurements.
"You have no idea what is going on between them. What the models are doing is trying to take the information we have from these two points and what we learned over the flight and to build a global heliosphere model to fit those observations. "