Heliosphere

Assembled from 23 blocks · 3 evidence · 9 related

1. Story
2. The bubble the solar wind blows in the interstellar medium, and the only structure that can honestly be called the Sun's domain. It is not bounded by gravity — the Sun's gravitational reach extends thousands of times further — but by pressure: the heliosphere ends where the outward push of the thinning solar wind can no longer hold back the plasma, magnetic field and cosmic rays of the surrounding Galaxy. It has internal structure that the Voyagers mapped by flying through it: supersonic wind out to the termination shock, then a thick, turbulent, subsonic heliosheath, then the heliopause itself. Because the Sun moves through the interstellar medium, the bubble is not spherical, and the two Voyagers crossed its boundary at different distances on different trajectories, which is part of how its shape is being reconstructed. Not a place.
3. Knowledge
4. Solar wind
5. Heliosphere
6. Very local interstellar medium
7. Connections
8. Very local interstellar medium
9. Solar wind
10. Termination shock
11. Heliopause
12. Voyager 2 crosses the termination shock at about 84 AU
13. Heliosphere
14. Heliopause
15. Voyager 1 crosses the heliopause at 121.6 AU
16. Voyager 2 crosses the heliopause at 119 AU
17. Heliosphere
18. Termination shock
19. Voyager 1 crosses the termination shock at about 94 AU
20. Evidence
21. Voyager 1's plasma wave instrument recorded electron plasma oscillations near 2.6 kHz in October–November 2012 and April–May 2013, implying an electron density of about 0.08 cm⁻³ and indicating that the spacecraft had been in interstellar plasma continuously since the boundary crossings of July–August 2012, dated 25 August 2012 at 121.6 AU. V55 verification basis: the paper is on a publisher domain blocked to this session, but search results carried the frequency, the density and the crossing date and distance and attributed them to this paper.
22. Voyager 2 crossed the heliopause on 5 November 2018 at 119 AU; a boundary layer about 1.5 AU wide preceded it in which the plasma slowed, heated and was roughly twice as dense as typical heliosheath plasma; the transition took less than a day, and the interstellar plasma immediately outside was hotter than predicted, of order 30,000–50,000 °C against a prediction nearer 15,000–30,000 °C. V55 verification basis: the paper was not fetched — nature.com is blocked to this session — but search results carried these figures and attributed them to it.
23. Voyager 1 crossed the solar wind termination shock on 16 December 2004 at about 94 AU and entered the heliosheath. V55 verification basis: NOT CHECKED IN THIS RUN. The session's search budget was exhausted before this crossing could be searched and the publisher domain is blocked; the citation is given from standard mission record without page numbers precisely because they were not confirmed. A curator must verify the date, the distance and the citation before publication.