Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

No meridional plasma flow in the heliosheath transition region


Over a two-year period, Voyager 1 observed a gradual slowing-down of radial plasma flow in the heliosheath to near-zero velocity1 after April 2010 at a distance of 113.5 astronomical units from the Sun (1 astronomical unit equals 1.5 × 108 kilometres). Voyager 1 was then about 20 astronomical units beyond the shock that terminates the free expansion of the solar wind and was immersed in the heated non-thermal plasma region called the heliosheath. The expectation from contemporary simulations2,3 was that the heliosheath plasma would be deflected from radial flow to meridional flow (in solar heliospheric coordinates), which at Voyager 1 would lie mainly on the (locally spherical) surface called the heliopause. This surface is supposed to separate the heliosheath plasma, which is of solar origin, from the interstellar plasma, which is of local Galactic origin. In 2011, the Voyager project began occasional temporary re-orientations of the spacecraft (totalling about 10–25 hours every 2 months) to re-align the Low-Energy Charged Particle instrument on board Voyager 1 so that it could measure meridional flow. Here we report that, contrary to expectations, these observations yielded a meridional flow velocity of +3 ± 11 km s−1, that is, one consistent with zero within statistical uncertainties.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Figure 1: Heliospheric plasma boundaries and flow regions relative to the location of Voyager 1.
Figure 2: Comparison of radial and azimuthal components of heliosheath plasma flow velocity at Voyager 2.
Figure 3: Roll measurements and derived components of heliosheath flow velocity.


  1. Krimigis, S. M., Roelof, E. C., Decker, R. B. & Hill, M. E. Zero outward flow velocity for plasma in a heliosheath transition layer. Nature 474, 359–361 (2011)

    Article  ADS  CAS  Google Scholar 

  2. Pogorelov, N. V., Borovikov, S. N., Zank, G. P. & Ogino, T. Three-dimensional features of the outer heliosphere due to coupling between the interstellar and interplanetary magnetic fields. III. The effects of solar rotation and activity cycle. Astrophys. J. 696, 1478–1490 (2009)

    Article  ADS  Google Scholar 

  3. Borovikov, S. N., Pogorelov, N. V., Burlaga, L. F. & Richardson, J. D. Plasma near the heliosheath: observations and modeling. Astrophys. J. 728, L21–L26 (2011)

    Article  ADS  Google Scholar 

  4. Gleeson, L. J. & Axford, W. I. The Compton-Getting effect. Astrophys. Space Sci. 2, 431–437 (1968)

    Article  ADS  Google Scholar 

  5. Richardson, J. D. & Wang, C. Plasma in the heliosheath: 3.5 years of observations. Astrophys. J. 734, L21–L24 (2011)

    Article  ADS  Google Scholar 

Download references


This work was supported at The Johns Hopkins University Applied Physics Laboratory by NASA contract NNN06AA01C. We thank J. Aiello for his assistance with our graphical presentation. We are grateful to the staff of the Voyager project for performing the Voyager 1 roll manoeuvres that made our analyses possible.

Author information

Authors and Affiliations



R.B.D. performed the data analysis and contributed to the text; S.M.K. contributed to the text; E.C.R. contributed to the text and provided theory interpretation; and M.E.H. analysed elemental composition.

Corresponding author

Correspondence to Robert B. Decker.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Decker, R., Krimigis, S., Roelof, E. et al. No meridional plasma flow in the heliosheath transition region. Nature 489, 124–127 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing