Heliosphere's Long-theorized Bow Shock Does Not Exist

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Discussion Overview

The discussion centers around the recent findings from NASA's Interstellar Boundary Explorer (IBEX) regarding the existence of the heliosphere's bow shock, a feature traditionally thought to precede the heliosphere as it interacts with interstellar gas and dust. Participants explore the implications of these findings, questioning the previous models and predictions related to the heliosphere and Voyager's position.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants note that new results from IBEX suggest the bow shock may not exist, contradicting previous assumptions.
  • One participant questions whether the bow shock could simply be absent, indicating uncertainty about its existence.
  • Another participant mentions a physicist's perspective that unexpected findings are beneficial for scientific progress, implying that the absence of the bow shock could lead to new insights.
  • There is a suggestion that if the bow shock is not present, only the heliopause remains, raising questions about the nature of the solar system's interaction with the interstellar medium.
  • A participant inquires about how the bow shock was initially predicted, suggesting that observations of other objects may have informed these predictions, yet finds it strange that Voyager 1 does not align with these expectations.
  • One participant proposes the idea of a bow wave instead of a bow shock, explaining the conditions under which each would occur based on the solar system's speed relative to the speed of sound in the interstellar medium.
  • Another participant provides a technical explanation of how IBEX measures interactions between solar wind and interstellar material, contributing to the understanding of the bow shock hypothesis.

Areas of Agreement / Disagreement

Participants express a range of views, with some supporting the idea that the bow shock does not exist, while others question the implications of this absence. The discussion remains unresolved regarding the nature of the solar system's boundary with the interstellar medium.

Contextual Notes

Participants highlight the limitations of current models and the dependence on observational data, noting that the absence of the bow shock raises further questions about the heliosphere's structure and the methods used to derive earlier predictions.

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"New results from NASA's Interstellar Boundary Explorer (IBEX) reveal that the bow shock, widely accepted by researchers to precede the heliosphere as it plows through tenuous gas and dust from the galaxy, does not exist." - Maria Martinez, SwRI Roadrunner, June 2012

So Voyager must actually be traversing some part of the heliopause rather than the bow shock front as has been reported in the popular press. Even NASA's own website has a story as recently as this spring that, while not specifically mentioning the theorized "bow shock" front, has an image depicting it. However, NASA's IBEX mission reports the solar system's bow shock front is reportedly missing.

Hmmm... curiouser and curiouser!
 
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Well, I don't know that much about this, but isn't there a chance that it just is that...missing? aka not there at all?
 
That seems to be the consensus.
 
I saw a documentary yesterday with a physicist saying that the best thing that can happen is when something isn't the way it's been predicted. If everything turned out to be exactly as predicted, physicists would soon run out of jobs.

Something like that anyway...

Now, what is there then if there is no bow shock?
 
Just the heliopause.
 
And how did they then derive the numbers to the fact that there should have been bow shock? From other objects they've observed? If so it seems weird that there would be non in relation to Voyager 1.

As said, I'm just curious and generally don't know anything about the topic... yet. Best way of learning is being curious! :)
 
Actually there may be a bow wave rather than a bow shock. A bow shock occurs if the solar system's speed through the interstellar medium is faster than the speed of sound in the interstellar medium while a bow wave will form if the speed of the solar system is slower than the speed of sound in the interstellar medium. So I guess it's likely that Voyager is actually moving through the bow wave rather than the bow shock.

edit. To answer your question regarding how the bow shock was measured, the IBEX spacecraft was designed to detect energetic neutral particles produced from an interaction between backscattered neutralized solar wind as that wind's ions are neutralized by incoming material from the interstellar medium. Ionized atoms in the solar wind (H+) are neutralized by a collision interaction with incoming neutral interstellar medium and the newly neutralized atom is reflected back toward the IBEX instrument with an energy that is a function of mass and relative velocity of the interacting species.
 
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Thanks for the link and explanation! Great info there going through the different sites there! I only read through a couple of them, but they did explain it in a nice and somewhat easily comprehensible way - for a noob.
 

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