Voyager 1 finally leaves the Solar System

[JazHaz]

According to the BBC, after 36 years, and many recent false alerts, Voyager 1 has left the solar system.

http://www.bbc.co.uk/news/science-environment-24026153

[JazHaz]

Here's another link, on the same story:

http://www.universetoday.com/104717/its ... lar-space/

[JensAyton]

According to JPL, Voyager has not left the solar system and won’t for 30,000 years. But they can now confidently say it’s in interstellar space, which ain’t the same thing.

[Cody]

<chortles> It's gotta pass through the Oort Cloud first (which is only theoretical), yes?

[JazHaz]

Yes the Oort Cloud is theoretical. No-one has detected any "cloud of comets", telescopically or otherwise. Perhaps the so-called "long period" comets actually come from interstellar space, and only approach the sun after being disturbed by other stars in our neighbourhood. 1.

In my view Voyager HAS left the solar system, as its outside the heliosphere. Yes, the sun will have a gravitational influence for many years, but then so will other stars in our neighbourhood, the pull of our Galaxy, and further than that our local group of galaxies, of which the Milky Way is only one. Gravity doesn't have a range of influence.

EDIT: If the theory of the Oort Cloud is correct, then other stars would have them too right? Trouble is, no-one has detected one. Kuiper Belts have been detected, but no Oort Clouds. 2.


References:
1. http://physics.stackexchange.com/questi ... oud-theory
2. http://www.berkeley.edu/news/media/rele ... iper.shtml

[JazHaz]

According to JPL, Voyager has not left the solar system and won’t for 30,000 years. But they can now confidently say it’s in interstellar space, which ain’t the same thing.

There is a big problem with that statement. Voyager is still in the solar system AND its in interstellar space? That's saying that interstellar space is inside the solar system. That doesn't sound right to me!

[JensAyton]

There is a big problem with that statement. Voyager is still in the solar system AND its in interstellar space? That's saying that interstellar space is inside the solar system. That doesn't sound right to me!

Interstellar space is defined in terms of the nature of the medium. The solar system is defined in terms of (possible) gravitational capture.

[JazHaz]

The solar system is defined in terms of (possible) gravitational capture.

Who says? Provide a reference?

[Disembodied]

The article from JPL says

So, would the team say Voyager 1 has left the solar system? Not exactly - and that's part of the confusion. Since the 1960s, most scientists have defined our solar system as going out to the Oort Cloud, where the comets that swing by our sun on long timescales originate. That area is where the gravity of other stars begins to dominate that of the sun. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it.

In other words, whether the Oort Cloud exists or nor (and detecting it would be extremely difficult, given that it would be very, very diffuse), the region where it is thought to be is the volume of space where our sun ceases to be the dominant local gravitational force (for a given value of "local" ).

The article goes on to say:

Informally, of course, "solar system" typically means the planetary neighborhood around our sun. Because of this ambiguity, the Voyager team has lately favored talking about interstellar space, which is specifically the space between each star's realm of plasma influence.

So, strictly and gravitationally speaking, the term "solar system" means "anywhere where the star Sol is the major gravitational player" - and Voyager has a looong way to go yet to reach somewhere where another star is outmuscling our sun. It's a collision between formal and informal language, really - a bit like why Pluto isn't a planet, any more: Pluto didn't change, but our formal definition of "planet" did.

[Cody]

... a bit like why Pluto isn't a planet, any more: Pluto didn't change, but our formal definition of "planet" did.

Ahh... poor old Pluto. At least now the planets again match The Planets (to which I happen to be listening as I type).

[Ranthe]

I have to admire the engineers who built Voyager - 35 years of continuous operation without any sort of service call in between. Hell, the thing was launched when I was in primary school, it did the Jupiter and Voyager encounters when I was in high school - and it's still going.

17 hours for a one-way transmission means that controlling it isn't so much remote control with a lag in steering as instructions via telegram

[Commander McLane]

17 hours for a one-way transmission means that controlling it isn't so much remote control with a lag in steering as instructions via telegram

Unfortunately, Western Union has canceled its telegram service on January 27th, 2006. So there's no way for NASA to deliver instructions by this method. Deutsche Post is still running its telegram service, but only domestically—which I guess doesn't cover the outer rims of the solar system. )

[JazHaz]

I have to admire the engineers who built Voyager - 35 years of continuous operation without any sort of service call in between. Hell, the thing was launched when I was in primary school, it did the Jupiter and Voyager encounters when I was in high school - and it's still going.

Not completely "going". The plasma instrument, which would have been very useful investigating interstellar space, stopped working a few years ago.