ⓘ Heliosphere. The heliosphere is a bubble in space blown into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar vo ..


ⓘ Heliosphere

The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can pass through this bubble, almost all of the material in the heliosphere comes from the Sun itself.

For the first ten billion kilometres of its radius, the solar wind travels at over a million kilometres per hour. As it begins to drop out with the interstellar medium, it slows down before finally stopping altogether. The point where the solar wind slows down is the termination shock ; the point where the interstellar medium and solar wind pressures balance is called the heliopause ; the point where the interstellar medium, travelling in the opposite direction, slows down as it collides with the heliosphere is the bow shock.


1. Solar wind

The solar wind is made of particles, chargedionized atoms from the solar corona, and fields, in particular magnetic fields. As the Sun rotates once in about 27 days, the magnetic field transported by the solar wind gets wrapped into a spiral. Differences in the Suns magnetic field are carried outward by the solar wind and can produce magnetic storms in the Earths magnetosphere.

In March 2005, measurements by the Solar Wind Anisotropies SWAN instrument onboard the Solar and Heliospheric Observatory SOHO have shown that the heliosphere, the solar wind-filled volume which prevents the solar system from becoming embedded in the local ambient interstellar medium, is not axisymmetrical, but is distorted, very likely under the effect of the local galactic magnetic field.


2. References and further reading

  • The Heliosphere Cosmicopia Archived 2019-09-04 at the Wayback Machine
  • The Heliosphere, MIT Space Plasma Group
  • "Heliopause Seems to Be 23 Billion Kilometres". Universe Today. December 9, 2003. Retrieved 2007-08-08.
  • Voyager Interstellar Mission Objectives
  • UIs Don Gurnett Says Voyager 1 Is Approaching Edge Of Solar System Archived 2006-02-09 at the Wayback Machine December 8, 2003 Univ. of Iowa Press release
  • "Space probes reveal Solar Systems bullet shape". COSMOS magazine. May 11, 2007. Archived from the original on 2007-05-13. Retrieved 2007-05-12.