Heliosphere's Long-theorized Bow Shock Does Not Exist

chemisttree

"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!

Storm89

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?

chemisttree

That seems to be the consensus.

Storm89

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?

chemisttree

Just the heliopause.

Storm89

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! :)

chemisttree

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.

Storm89

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.