> Interstellar space begins where the heliosphere ends. But by some measures, Voyager 1 remains inside the solar system, which is surrounded by a shell of comets known as the Oort Cloud.
See you next July! I look forward to reading this story every year for the next 50 years or so. Maybe I'll pass it in some spaceship and be reading stories about how it's leaving the solar system.
To be fair, they aren't saying it just happened. They are confirming their last announcement that it had left the solar system. They are just saying they are more sure.
However, for humor's sake, I also had thoughts pretty much along the line of yours when I read the headline.
not to mention the other 15 dozen times they announced it 'may' have left the solar system. then they are like it left the solar system, and more recent, we are even more sure it left the solar system, like really this time
Maybe a mission to the Oort cloud in the distant future will do a fly-by of Voyager. This would feel a little bit like sending out a jet plane and seeing Magellan still making his way around the world.
The article confirms that it left the Heliosphere at Augst 2012. Nobody was sure before, some people are sure now. But I'll bet some still aren't, so we'll probably read about it again.
Also, if you plan to wait it to live the Oort Cloud, you'd beter invest some time pushing up cryogenics or imortality.
I do not mind reading about this every year, even if it is the same news and 'nothing new to see here'
Just being reminded about Voyager and the vastness and other miracles of space helps put that daily to-do list in perspective. For me anyway. Your mileage may vary, no pun intended.
I'm not really informed about these things, but if you asked me for my opinion... Voyager 1 is not out of our solar system until it's caught in the gravity of another one. In other words, if it was possible to bring it to a full stop and take a measurement, when gravity pulls it in another direction away from our sun, it is outside. That could be quite some time longer?
I don't think that's a fair assessment. It would be like saying you haven't left your town until you see another one.
And bringing Voyager I to a full stop is currently impossible. It doesn't have the fuel and is traveling at incredible speed. Although, technically the velocity is relative to our own. It very well may BE stopped relative to some other object in space.
If it were pointing at Proxima Centauri, the nearest star system to ours, it would take 75,000 years, give or take, to get there.
I don't think that's a useful measurement, because solar systems are too far apart. You can leave a solar system and then travel a long time before you get to another.
For fun I calculated the hill sphere for an atom out there.
His distance is awful close to 1e16 meters. Figure an atom of H weights 6e-23 (ha ha we'll ignore isotopes) (edited note, well, thats embarassing, but no one else will notice, not here on HN anyway, and it doesn't change the result, so I'm not redoing the arithmetic in my head again). Guess the mass of the sun at 2e30
So the Hill radius would be 1e16 (6e-23 / (3 * 2e30) ) ^ 1/3 and that works out to like 3e-38 meters or so? And if an atomic bond is like "hundreds of picometers" that means that there's no real possible way for two hydrogen atoms to stably orbit each other gravitationally without influence from the sun at 100000 AU. They could get into a chemical bond, sure, which would gravity gradient stabilize... eventually. But the sun is going to be a part of the party.
If you tossed the earth out there, this close in right now our hill sphere is like 1.5e6 meters, but way out there it would be like 3e9 meters which is pretty big, ridiculous close (well, to one sig fig) to neptune's orbit. So assuming he didn't pick a random number, that does work out that if you tossed the earth that far away from the sun, the earth's little "solar system" of junk orbiting it without interference from the far away sun, would be about the size of the solar system. Which I guess means something, although not much.
I actually think it's fairly exciting they're still collecting data from this thing, data that allow them to say with increasing confidence that it's in interstellar space.
The speed it already has. There's practically no friction in space, so any speed it picked up from its engines and gravitational slingshots is kept. Newton's first law.
that's a good point. It's impossible to measure the effect of this on the Voyagers because they still constantly fire attitude control thrusters to align themselves to earth. The noise on the speed from those firings is too much to distinguish solar radiation pressure.
Actually they can measure this with great precision. Consider how they were able to isolate the "Pioneer Anomaly" (http://en.wikipedia.org/wiki/Pioneer_anomaly), an extremely tiny amount of deceleration caused by radiation from the reactor.
If they can measure the drag caused by radiation, you can bet they can account for solar effects.
Also worth noting: The thrusters are fired very infrequently. According to that page, the Voyager missions required constant adjustments but the Pioneer system is spin stabilized.
That's exactly the problem. Because Pioneer was spin-stabilized, it didn't need to fire thrusters, so the noise wasn't there and the anomaly could be measured. Voyagers aren't spin-stabilized, so they have to fire thrusters quite frequently. That makes it impossible to measure a small enough effect on them.
Oh crap. Now we've done it. This thing is going to encounter an alien race of machines, get smart, and come back and hold the earth hostage while looking for it's long lost creator!
See you next July! I look forward to reading this story every year for the next 50 years or so. Maybe I'll pass it in some spaceship and be reading stories about how it's leaving the solar system.