3 ms·

That makes sense as far as explaining another situation where you would see a similar pattern, but it doesn't really explain why. What's the equivalent of the l

That makes sense as far as explaining another situation where you would see a similar pattern, but it doesn't really explain why. What's the equivalent of the land surrounding the cove here? The sun's gravity well? But that's a gradual drop-off, are we looking at the distance where the gravitational pull on particles is canceled out by some other force?

ikiris 3y ago
Hydraulic Jump on interstellar scale. Heliopause. The heliopause is the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium; where the solar wind's strength is no longer great enough to push back the stellar winds of the surrounding stars. This is the boundary where the interstellar medium and solar wind pressures balance.
- ryanjshaw 3y ago
  But again, why is it a sudden cut-off and not a gradual one?
  - danbruc 3y ago
    Have look at your sink [1], it is called termination shock. [2] [1] https://en.wikipedia.org/wiki/Heliosphere#/media/File:Heliosphere-washbasin.svg https://en.wikipedia.org/wiki/Heliosphere#/media/File:Helios... [2] https://en.wikipedia.org/wiki/Heliosphere#Termination_shock https://en.wikipedia.org/wiki/Heliosphere#Termination_shock
- sanderjd 3y ago
  Interesting! What is the interstellar medium? Is it entirely the combined stellar winds of all the other stars, or are there other components? My initial intuition was to wonder why the vectors of all the other stellar winds wouldn't be expected to nearly cancel each other out, but then it seems like the ones that would be pushing in the same direction as the sun's would have been blocked on the other side of the sphere, so it does seem to make sense that the net direction would be to point inward. But then I realized that I have no idea if any of that reflects an accurate mental model of what's going on :)
ineptech 3y ago
AIUI, the solar wind does attenuate gradually; the relatively sharp drop-off is the transition from the "I feel the solar wind more than the interstellar medium" region to the "I feel the ISM more than solar wind" region.

ikiris 3y ago

Hydraulic Jump on interstellar scale. Heliopause. The heliopause is the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium; where the solar wind's strength is no longer great enough to push back the stellar winds of the surrounding stars. This is the boundary where the interstellar medium and solar wind pressures balance.

ryanjshaw 3y ago
But again, why is it a sudden cut-off and not a gradual one?
- danbruc 3y ago
  Have look at your sink [1], it is called termination shock. [2] [1] https://en.wikipedia.org/wiki/Heliosphere#/media/File:Heliosphere-washbasin.svg https://en.wikipedia.org/wiki/Heliosphere#/media/File:Helios... [2] https://en.wikipedia.org/wiki/Heliosphere#Termination_shock https://en.wikipedia.org/wiki/Heliosphere#Termination_shock
sanderjd 3y ago
Interesting! What is the interstellar medium? Is it entirely the combined stellar winds of all the other stars, or are there other components? My initial intuition was to wonder why the vectors of all the other stellar winds wouldn't be expected to nearly cancel each other out, but then it seems like the ones that would be pushing in the same direction as the sun's would have been blocked on the other side of the sphere, so it does seem to make sense that the net direction would be to point inward. But then I realized that I have no idea if any of that reflects an accurate mental model of what's going on :)

ineptech 3y ago

AIUI, the solar wind does attenuate gradually; the relatively sharp drop-off is the transition from the "I feel the solar wind more than the interstellar medium" region to the "I feel the ISM more than solar wind" region.