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posted by Fnord666 on Thursday October 22 2020, @10:46AM   Printer-friendly
from the that's-why-they-call-it-a-pause dept.

Voyager Spacecraft Detect an Increase in The Density of Space Outside The Solar System:

In November 2018, after an epic, 41-year voyage, Voyager 2 finally crossed the boundary that marked the limit of the Sun's influence and entered interstellar space. But the little probe's mission isn't done yet - it's now sending home information about the space beyond the Solar System.

And it's revealing something surprising. As Voyager 2 moves farther and farther from the Sun, the density of space is increasing.

It's not the first time this density increase has been detected. Voyager 1, which entered interstellar space in 2012, detected a similar density gradient at a separate location.

Voyager 2's new data show that not only was Voyager 1's detection legit, but that the increase in density may be a large-scale feature of the very local interstellar medium (VLIM).

[...] One theory is that the interstellar magnetic field lines become stronger as they drape over the heliopause. This could generate an electromagnetic ion cyclotron instability that depletes the plasma from the draping region. Voyager 2 did detect a stronger magnetic field than expected when it crossed the heliopause.

Another theory is that material blown by the interstellar wind should slow as it reaches the heliopause, causing a sort of traffic jam. This has possibly been detected by outer Solar System probe New Horizons, which in 2018 picked up the faint ultraviolet glow resulting from a buildup of neutral hydrogen at the heliopause.

It's also possible that both explanations play a role. Future measurements taken by both Voyager probes as they continue their journey out into interstellar space could help figure it out. But that might be a long bet to take.

"It is not certain," the researchers wrote in their paper, "whether the Voyagers will be able to operate far enough to distinguish between these two classes of models."


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  • (Score: 2) by EJ on Thursday October 22 2020, @01:11PM (2 children)

    by EJ (2452) on Thursday October 22 2020, @01:11PM (#1067481)

    We don't really know what space is made of.

    Imagine the universe is the ocean, and we live at the center of a bubble. Inside the bubble, there is no water for us to observe, because the air of the bubble keeps it all out. Everything our science knows about is based solely on inside-the-bubble physics. Our sun creates the bubble, so we cannot experience anything about existence outside this bubble until we go there.

    We think that space is a vacuum, but we don't really know what a vacuum is. There isn't actually "nothing" inside a vacuum. There is space inside the vacuum, and space is "something."

    Until we get a probe far enough outside our solar system to take actual measurements, we will continue to have no real knowledge of what interstellar space is actually made of. Intergalactic space is another matter(no pun intended) entirely.

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  • (Score: 2) by Runaway1956 on Thursday October 22 2020, @01:49PM

    by Runaway1956 (2926) Subscriber Badge on Thursday October 22 2020, @01:49PM (#1067499) Journal

    All true. But, add a layer to that. Our bubble lies right at the edge of a galaxy. When we have determined conditions outside of our bubble within the galaxy, we may or may not have some idea of conditions between galaxies. All of that "missing matter" may well be right there, in plain sight, but we don't understand how to look for it.

  • (Score: 0) by Anonymous Coward on Friday October 23 2020, @02:15PM

    by Anonymous Coward on Friday October 23 2020, @02:15PM (#1067875)

    Hmmmm, this doesn't bode well for us now that the Voyagers have poked two holes in the bubble to let the space in.