Voyager 1 Explores the Termination Shock Region and the Heliosheath Beyond

@article{Stone2005Voyager1E,
  title={Voyager 1 Explores the Termination Shock Region and the Heliosheath Beyond},
  author={Edward C. Stone and Alan C. Cummings and Frank B. Mcdonald and Bryant C. Heikkila and N. K. Lal and W. R. Webber},
  journal={Science},
  year={2005},
  volume={309},
  pages={2017 - 2020}
}
Voyager 1 crossed the termination shock of the supersonic flow of the solar wind on 16 December 2004 at a distance of 94.01 astronomical units from the Sun, becoming the first spacecraft to begin exploring the heliosheath, the outermost layer of the heliosphere. The shock is a steady source of low-energy protons with an energy spectrum ∼E–1.41 ± 0.15 from 0.5 to ∼3.5 megaelectron volts, consistent with a weak termination shock having a solar wind velocity jump ratio \batchmode \documentclass… 
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Voyager observations of the interaction of the heliosphere with the interstellar medium
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Observations from Voyager 1 are interpreted as evidence that V1 was crossed by the TS on 2004/351 (during a tracking gap) at 94.0 astronomical units, evidently as the shock was moving radially inward in response to decreasing solar wind ram pressure, and that V 1 has remained in the heliosheath until at least mid-2005.
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