Hacker News Reader

Hacker News

Comment by js2 | Hacker News Reader

Full thread

js2

Previous times it has left:

- https://news.ycombinator.com/item?id=4867577 (106 days ago)

- https://news.ycombinator.com/item?id=4619731 (165 days ago)

- https://news.ycombinator.com/item?id=4483757 (195 days ago)

Seems like we're still not sure it's left due to lack of agreement on what constitutes leaving:

However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system.

View on HN

There was some great discussion on what "leaving" might mean. And several theories about how that might show up on the instruments. Each time the instrument readings changed the scientists asked the question "So does this mean we're outside?" and in the ensuing discussion concluded that Voyager was still travelling through the boundary layer. An astrophysicist at Berkeley described it like leaving the ocean, when you're coming up on the beach but your still being washed over by waves are you in the ocean or not? Sometimes are sometimes not? Hard to say if you've never seen a beach and the only communication you get back from your probe is "I'm wet!","I'm not wet!"

This is likely one of the last "we think we're outside" papers I suspect. From the paper:

"This large decrease of ACR was preceded by 2 precursor temporary decreasesstarting on July 28th and August 14th. Thus V1 may have crossed a boundary, which itself was very sharp, at least 5 times during this time period"

(V1 = Voyager 1, ACR = Anomalous Cosmic Rays)

Phil Plait of Bad Astronomy has come down on the "this time it's for real" side of things. The graph he shows seems pretty convincing:

http://www.slate.com/blogs/bad_astronomy/2013/03/20/voyager_...

Really?

>[Update/Correction (Mar. 19, 2013): I wrote the piece below after reading a press release from the American Geophysical Union (AGU) and after reading the professional science journal paper announcing the results. Just after posting this I received a press release from NASA/JPL quoting Ed Stone, the Voyager project scienist, saying "It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space.... [Emphasis mine.] I then received a follow-up press release from the AGU also backing off the claim of Voyager leaving the solar system.... So to be clear, the science of what I describe below is accurate enough, but the idea that Voyager 1 has left the building is not.

My guess, is that Voyager being declared "outside" the solar system will happen only after quite of bit of time has passed since it actually left. Like the Higgs Boson, there is data, there is analysis, and there are confidence intervals. One result may be that the instruments send back cosmic ray information that no theory can explain how that would be consistent with being inside the heliosphere. Or it may simply be that the environment stops changing. And after a while that non-changing result is accepted as being "outside" and then you can walk backwards in the data to figure out the first time you got that result (and consequently the last change you saw) and declare the exit that way.

They called in the big guns. Here's the correcting press release:

http://www.jpl.nasa.gov/news/news.php?release=2013-107

Ed Stone, the project scientist and the nominal author of this press release, is 77 now. He was 41 when Voyager 1 launched (and he was project scientist then, too). You still see him around JPL and Caltech.

So it's out of the solar system - but is it in interstellar space?

Reading the Bad Astronomy blog entry got me thinking about the Oort Cloud - perhaps that is the real interstellar space (within the galactic plane) - beyond the Bow Shock and at a size of 1.5-3.0 LY with a spherical distribution, the cloud edge is closer to some of our nearest stars (notably Alpha Centauri, whose binary mass is 2 solar masses) than to the sun.

Perhaps the Oort Cloud is interestellar space - in which case, V1 hasn't gotten there yet.

Are you saying that our Oort Cloud potentially intersects with Oort Clouds of other stars? I didn't realize it was that big. Maybe interstellar space is ALL Oort Cloud, and we just haven't noticed because the masses are too small and cold to see (and obscured by closer stuff.) Maybe that's enough to make up the dark matter mass?

All four articles are talking about the same event that happened in August 2012. Today's article is a press release from the journal where the scientists published the data.

Maybe Voyager 1 keeps coming back then leaving again? :)

Are they using a reentrant space probe?

Did they send Schrödinger's cat with Voyager 1?

We'll never know.

Maybe this a hidden new feature of gravity, and it is impossible to get out of the heliosphere. OMG it's a trap.

"Seems like we're still not sure it's left due to lack of agreement on what constitutes leaving"

It's like leaving a country by staying in place while the borders are being redrawn on the map. ;)

Almost. It's more accurate to say you're inching away from the capital in an outward direction very slowly, while the borders are redrawn around you.

Not according to NASA, and they should know best:

http://au.news.yahoo.com/thewest/a/-/news/16411537/nasa-deni...

Reply on news.ycombinator.com