Has Voyager1 really left the Solar System

This must be the 10th time or so we hear the news that NASA’s Voyager 1 has left the Solar System to continue on into inter-stellar space - to boldly go where no man has gone before.  Too bad it wasn’t fitted with a warp drive.
:-P

Over the years, I remember three prominent reports of Voyager 1 leaving the Solar System.

• Nature in 2003 said that Voyager 1 is probing the edge of the solar system;
• In 2005 Voyager mission Chief Scientist Edward Stone announced that the spacecraft has suffered termination shock from Solar Wind;
• Same Ed Stone in 2010 waxed eloquent that the solar wind around Voyager 1 is pushing outward no more, but flowing sideways;

To be fair to the scientists, none of them actually used the phrase ‘left-the-solar-system’ - they have been careful to insist that Voyager 1 is at the boundary.  ‘Left- the-solar-system’ was (and still is) media hype.

So how is the present announcement, that Voyager 1 has ‘left-the-solar-system’ any different?

Actually it is and it isn’t. 

• It is different in the sense the Voyager team finally agree that Voyager 1 has broken through the heliosphere into outer space.  They are confident because measured electron density around Voyager 1 are at levels predicted for interstellar space.
• It is the same as other earlier announcements, because the space craft is in interstellar space, but has *not* yet left the Solar System.

Confused whether Voyager 1 is out of the solar system or not?  It is and it isn’t. In simple terms:

• If we think of the Solar System as taught in high school (and what the media talks about) - the Sun, with 9 (or is it 8?) planets, within the Sun’s radiation bubble called heliosphere - then Voyager 1 is out of it.
• But technically, solar system is defined as including the Oort Cloud - a massive spherical collection of icy planetoids (from which comets are supposed to originate), within the Sun’s gravitational bubble - and so Voyager 1 is still inside it.

As for the news itself, I couldn’t help but laugh at this XKCD cartoon on the subject.  Don’t miss the pop-up comment at the XKCD. /really love it/

Tags: voyager_1,oort_cloud,heliosphere,edward_stone

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