[neilep (OP)]

Dear Peeps Of My Respek and Academic Distinguishment,




Take a look at this bona-fide piccy I just took of Voyager 1 just moments ago.





Voyager One (or two...I didn't ask )  Just Moments ago




Why do they say Voyager 1 and 2 are in interstellar space when they have not passed the Oort cloud ?


what's that all about ? Should not Interstellar Space be PAST the OOOOOORRRTTTTTTT CLOUD ?


whajafink ?

[Halc]

Why do they say Voyager 1 and 2 are in interstellar space when they have not passed the Oort cloud ?

Apparently the heliopause defines the boundary of the solar system vs interstellar space.  The sun puts out a solar wind which forms a sort of shock wave as it pushes against the interstellar medium.  Beyond the heliopause, this wind is no longer capable of resisting said medium and particles out there come from pretty much anywhere.

Voyager 1 seems to be sending back messages that the system that keeps the probe correctly oriented has failed.
Funny thing is that the message couldn't have been sent if that was actually true. So it seems to be functioning, but it doesn't know that it's functioning.

[Bored chemist]

Voyager 1 seems to be sending back messages that the system that keeps the probe correctly oriented has failed.
Funny thing is that the message couldn't have been sent if that was actually true. So it seems to be functioning, but it doesn't know that it's functioning.

The equivalent of a zoom call "I can't hear you: can you hear me?"

[evan_au]

There are many ways to define the edge of the Solar System:
- The outermost planet, which kept creeping further outwards (until Pluto was demoted); but some astronomers are still searching for Planet X.
- Where the solar wind dominates: But this probably changes over time; I imagine that during the Maunder Minimum, this was considerably closer to the Sun.
- Where the Sun's magnetic field dominates: The solar wind also carries traces of the Sun's magnetic field. At the edge of the heliosphere, the galaxy's magnetic field starts to dominate. But this edge is turbulent, which is why they announced crossing into interstellar space several times (and then took it back, but more quietly).
- Where the Sun attracts an an object more strongly than another star. This is about half the distance to  the nearest star in that direction, if the stars were of a similar mass.  (Note that the Sun's attraction on Oort Cloud objects is not as strong as the gravitational tug of the galactic center, which is bending the path of all nearby matter into an orbit around the galaxy).
- The Kuiper Belt is a disk of icy objects extending outwards beyond Neptune. No current human space probes have reached the outer edge of the Kuiper Belt. But large telescopes have detected many objects in this region.
- The Oort Cloud is a hypothetical sphere of icy objects between the stars. They are so distant and so rare that we can't readily observe them even with large telescopes. Occasionally an Oort Cloud object will be deflected into the inner Solar System as a long-period comet. The Oort Cloud extends outwards until it gradually merges into the Oort Cloud of the next star. In between, some icy objects will be orbiting the galaxy rather than any particular star, and wandering between the stars.

So I suggest that since the Oort Cloud fills interstellar space; once you are in the Oort Cloud, you are in interstellar space. NASA wanted a headline before Voyager's nuclear batteries finally die, so they decided that the edge of the Sun's magnetic field was a more "newsworthy" criterion (and recyclable, to boot!).

https://en.wikipedia.org/wiki/Kuiper_belt
https://en.wikipedia.org/wiki/Oort_cloud