First Images of Solar System's Invisible Frontier

FiReaNGeL writes an unexpected side-effect from NASA's STEREO spacecraft has allowed scientists to see a much more well-defined picture of the boundary of our solar system. "The twin STEREO spacecraft were launched in 2006 into Earth's orbit about the sun to obtain stereo pictures of the sun's surface and to measure magnetic fields and ion fluxes associated with solar explosions. Between June and October 2007, however, the suprathermal electron sensor in the IMPACT (In-situ Measurements of Particles and CME Transients) suite of instruments on board each STEREO spacecraft detected neutral atoms originating from the same spot in the sky: the shock front and the heliosheath beyond, where the sun plunges through the interstellar medium."

Acronym in an Acronym?

IMPACT (In-situ Measurements of Particles and CME Transient)

Dear God, an acronym inside another acronym! I think the space geeks have beat us computer geeks yet again.

Re:Acronym in an Acronym?

Meh. It doesn't even recurse like GNU's Not Unix.

Re:

Just wait 'til they come up with something like GNW's Not WINE.

Re:Acronym in an Acronym?

And apparently XINU Is Not Unix, either.

Of course not, Evil Galactic Overlords always use Windows.

Re:Acronym in an Acronym?

It's acronyms all the way down...

Re:Acronym in an Acronym?

((GNU's Not Unix) Image Manipulation Program) Tool Kit

Can't think of something that uses GTK or I'd continue the fun!

And a sign that reads...

Last chance for gas, 20,000,000,000 km. We have lotto tickets and cold beer!

Images of an invisible frontier?

Would that be like recordings of silence or the smell of nothing?

Re:Images of an invisible frontier?

The sound of one hand clapping.

Re:Images of an invisible frontier?

Also from TFA "The termination shock is the region of the heliosphere where the supersonic solar wind slows to subsonic speed"

Last I checked wasn't sonic speed something only relative to earth? Wouldn't that make this point completly arbitrary in a cosmic sense?

This was covered in the Slashdot post a while back about Voyager 2 crossing the termination shock. It boils down to the fact that the plasma from the solar wind does conduct waves, although due to the density of the particles and the nature of a plasma, the waves are much faster than the speed of sound through earth's atmosphere. So sonic speed does have a point (and related phenomena in this context. See this article [space.irfu.se], or google "super sonic speed heliopause".

Sloar system's velocity

Wouldn't it be possible, using the sun as a center point, to measure the distance to the termnation shock vs the boundaries of the heliosphere to determine how fast and in what vector our solar system is moving through space relative to the center of our galaxy? Or has this already been done, 'cause I can't find the info.
Possibly, using this information, couldn't an orbital pattern of our solar system be extrapolated against the center of the galaxy as a reference point?

Re:Sloar system's velocity

I'm sure it's possible, but pointless. Decades ago, astronomers mapped proper motion and showed that all the stars were streaming away from a single point in the constellation Hercules. Presumably, that's where we're headed.

Re:Sloar system's velocity

I'm sure it's possible, but pointless. Decades ago, astronomers mapped proper motion and showed that all the stars were streaming away from a single point in the constellation Hercules. Presumably, that's where we're headed.

      Makes you think, doesn't it? Everyone is getting the hell out of there and we're headed straight for it. Someone ought to do something about this... :)

Re:Solar system's velocity

Well, the gas into which the Sun is driving the termination shock could also have a mean motion relative to the Keplerian velocity at its distance from Galactic center so...no.

However, the Sun's motion relative to the Galactic center is reasonably well known. It is based on looking at the velocities of stars in the local neighborhood (which should be in the same general orbit around Galactic center), and assuming that the average of these would be zero IF the Sun had no velocity except that required for its orbit around Galactic center. The average isn't, so the Sun has an extra velocity component, which is just the negative of this average. (The technical terms used for these quantities are the "solar motion" and the "Local Standard of Rest".) It turns out to be around 16.5 km/sec diagonally inward and slightly upward from its rotation.

Re:

Have a look at this:
http://adsabs.harvard.edu/abs/1998MNRAS.298..387D

A Terry Gilliam fan writes

"Ah, so *that's* what an invisible frontier looks like!"

the question is..

...what does god need with a Twin Stereo Starship?

Math Quiz

TFA: The termination shock is the region of the heliosphere where the supersonic solar wind slows to subsonic speed as it merges with the interstellar medium.

Okay boys and girls. Quick, grab your calculator and calculate the speed of sound in space...

Re:Math Quiz

c = (k p / Ï)^1/2

Put in the numbers and get your answer. The speed of sound in space works out to around 300 m/s in these parts.

Or were you under the impression that sound isn't transmitted in space? Sound we can hear isn't, but the ambient gas in space certainly does transmit disturbances, and will let you know if something passing through it exceeds the speed of sound by forming a shock wave.

nice picture...

I was expecting a picture that didn't look like something I drew today at work using MS Excel and autoshapes.

Re:

It, grasshopper, is the sound of one star clapping.

Re:Woooooosh

Interstellar space isn't empty. You have nebula and lots of (hundreds of billions?) stars spewing particles just like the Sun does, etc. So there is something for the solar wind to run into.

Re:Woooooosh

In our neighbourhood it's a a lot less dense [berkeley.edu] than average.

Even taking the average of about 1 hydrogen atom per cc, if you had a tube 1 cm in diameter that stretched from here to Alpha Centauri, the total mass inside the tube would be 3e-12 grams.

So yes theres stuff out there, but it wouldn't ruffle your hair if you put the convertible top down on your spaceship.

Re:Woooooosh

It's the boundary where the charged particles that make up the solar wind get blasted by the galactic wind. Somewhere on the perimeter of the galaxy, there will be a similar shock boundary where the galactic winds become too faint and get ripped sway by the intergalactic winds. The solar winds are supposed to offer considerable protection from the galactic winds and I seem to recall hearing that probes that go outside of the heliopause will need far more extensive shielding from radiation to handle the conditions they will meet.

Re:Hot, that's really hot!

http://www.thebestpageintheuniverse.net/c.cgi?u=puns [thebestpag...iverse.net]