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.

  • Letter
  • Published:

The optical polarization of the Sun measured at a sensitivity of parts in ten million

An Erratum to this article was published on 02 July 1987

A Corrigendum to this article was published on 02 July 1987

This article has been updated


The integrated light of the Sun, an essentially spherical star with only slight asymmetries (small oblateness, weak overall magnetic field), would normally be found to be unpolarized, as observed in broad spectral bands with common instrumental sensitivities, 10−4−10−5 fractional polarization1–4. Defining the Sun's intrinsic linear (LP) and circular (CP) polarizations down to much lower levels (10−7 or even 10−8) would have consequences not only in solar physics but in other areas, setting, for example, a new standard for stellar polarimetry. We report measurements of the general polarization of the Sun, both CP and LP, over the whole disk and over large sectors, at an absolute sensitivity level of 3×10−7, carried out during August–September 1986. Upper limits for the intrinsic whole-Sun LP from the best data (minimum Earth-atmospheric contamination) were 0.2×10−6 in the V (yellow) band and 0.8×10–6 in B (blue). Definite CP was discovered. (1) The north and south polar zones showed values of V (normalized or fractional CP) of −1 to −6×10−6 for the north, and 0 to +2×10−6 for the south zones. The spectral CP rises steeply toward the blue. (2) The whole disk had a net CP of −0.1 to −1.0×10−6 (from red to blue), negative as with the magnetically dominant north pole. The spectral dependence of the global broadband CP resembles that of sunspots5,6 and of local non-spot regions with magnetic flux tubes7.

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

Access options

Buy this article

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

Similar content being viewed by others

Change history


  1. Dollfus, A. in Planets, Stars and Nebulae Studied with Photopolarimetry (ed. Gehrels, T.) 695–729 (Univ. Arizona Press, Tucson, 1974).

    Google Scholar 

  2. Kemp, J. C. & Barbour, M. S. Publs astr. Soc. Pacific 93, 521–525 (1981).

    Article  ADS  Google Scholar 

  3. Kemp, J. C. Proc. Soc. photo-opt. Instrum. Eng. 307, 83–88 (1981).

    Google Scholar 

  4. Tinbergen, J. Astr. Astrophys. 105, 53–64 (1982).

    ADS  Google Scholar 

  5. Kemp, J. C. & Henson, G. D. Astrophys. J. 266, L69–L72 (1983).

    Article  ADS  Google Scholar 

  6. Henson, G. D. & Kemp, J. C. Sol. Phys. 93, 289–299 (1984).

    Article  ADS  Google Scholar 

  7. Stenflo, J. O. Appl. Opt. 23, 1267–1278 (1984).

    Article  ADS  CAS  Google Scholar 

  8. Kemp, J. C., Wolstencroft, R. D. & Swedlund, J. B. Astrophys. J. 177, 177–189 (1972).

    Article  ADS  Google Scholar 

  9. Stokes, R. A., Ekstrom, P. A. & Swedlund, J. B. Opt. Eng. 15, 7–11 (1976).

    Article  ADS  Google Scholar 

  10. Cheng, J. C., Nafie, L. A. & Stephens, P. J. J. opt. Soc. Am. 65, 1031–1035 (1975).

    Article  ADS  CAS  Google Scholar 

  11. Coulson, K. L. in Planets, Stars and Nebulae Studied with Photopolarimetry (ed. Gehrels, T.) 444–471 (Univ. Arizona Press, Tucson, 1974).

    Google Scholar 

  12. Pierce, A. K. Astrophys. J. 120, 221–232 (1954).

    Article  ADS  Google Scholar 

  13. Hoeksema, J. T. & Scherrer, P. H. The Solar Magnetic Field—1976 through 1985 (Report UAG-94, Natn. Geophysical Data Center, Boulder, USA, 1976).

    Google Scholar 

  14. Stenflo, J. O., Harvey, J. W., Brault, J. W. & Solanki, S. Astr. Astrophys. 131, 333–346 (1984).

    ADS  CAS  Google Scholar 

  15. Stenflo, J. O. & Harvey, J. W. Sol. Phys. 95, 99–118 (1985).

    Article  ADS  CAS  Google Scholar 

  16. Auer, L. H. & Heasley, J. M. Astr. Astrophys. 64, 67–71 (1978).

    ADS  Google Scholar 

  17. Stenflo, J. O., Solanki, S. K. & Harvey, J. W. Astr. Astrophys. (in the press).

  18. Stenflo, J. O. in Basic Mechanism of Solar Activity (eds Bumba, V. & Kleczek, W.) 69–99 (Reidel, Dordrecht, 1976).

    Book  Google Scholar 

  19. Roberts, C. K. & Boksenberg, A. (eds) The Astronomical Almanac 1986 C15 (US Govt Printing Office and HMSO, 1986).

  20. Mullan, D. J. Astrophys. J. 279, 746–747 (1984).

    Article  ADS  Google Scholar 

  21. Giampapa, M. S., Golub, L. & Worden, S. P. Astrophys. J. 268, L121–L125 (1983).

    Article  ADS  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Reprints and permissions

About this article

Cite this article

Kemp, J., Henson, G., Steiner, C. et al. The optical polarization of the Sun measured at a sensitivity of parts in ten million. Nature 326, 270–273 (1987).

Download citation

  • Received:

  • Accepted:

  • 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