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Earth’s transmission spectrum from lunar eclipse observations


Of the 342 planets so far discovered1 orbiting other stars, 58 ‘transit’ the stellar disk, meaning that they can be detected through a periodic decrease in the flux of starlight2. The light from the star passes through the atmosphere of the planet, and in a few cases the basic atmospheric composition of the planet can be estimated3,4,5. As we get closer to finding analogues of Earth6,7,8, an important consideration for the characterization of extrasolar planetary atmospheres is what the transmission spectrum of our planet looks like. Here we report the optical and near-infrared transmission spectrum of the Earth, obtained during a lunar eclipse. Some biologically relevant atmospheric features that are weak in the reflection spectrum9 (such as ozone, molecular oxygen, water, carbon dioxide and methane) are much stronger in the transmission spectrum, and indeed stronger than predicted by modelling10,11. We also find the ‘fingerprints’ of the Earth’s ionosphere and of the major atmospheric constituent, molecular nitrogen (N2), which are missing in the reflection spectrum.

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Figure 1: Earth’s visible and near-infrared transmission and reflection spectra.


  1. The. Extrasolar Planets Encyclopaedia. 〈〉 (accessed 18 March 2009)

  2. Seager, S. & Sasselov, D. D. Theoretical transmission spectra during extrasolar giant planet transits. Astrophys. J. 537, 916–921 (2000)

    Article  CAS  ADS  Google Scholar 

  3. Charbonneau, D., Brown, T. M., Noyes, R. W. & Gilliland, R. L. Detection of an extrasolar planet atmosphere. Astrophys. J. 568, 377–384 (2002)

    Article  CAS  ADS  Google Scholar 

  4. Tinetti, G. et al. Water vapour in the atmosphere of a transiting extrasolar planet. Nature 448, 169–171 (2007)

    Article  CAS  ADS  Google Scholar 

  5. Swain, M. R., Vasisht, G. & Tinetti, G. The presence of methane in the atmosphere of an extrasolar planet. Nature 452, 329–331 (2008)

    Article  CAS  ADS  Google Scholar 

  6. Mayor, M. et al. The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 super-Earths (4.2, 6.9, and 9.2 ME). Astron. Astrophys. 493, 639–644 (2009)

    Article  CAS  ADS  Google Scholar 

  7. Borde, P., Rouan, D. & Leger, A. Exoplanet detection capability of the COROT space mission. Adv. Space Res. 405, 1137–1144 (2003)

    Google Scholar 

  8. Basri, G., Borucki, W. J. & Koch, D. The Kepler Mission: A wide-field transit search for terrestrial planets. N. Astron. Rev. 49, 478–485 (2005)

    Article  ADS  Google Scholar 

  9. Montañés-Rodríguez, P., Palle, E., Goode, P. R., Hickey, J. & Koonin, S. E. Globally integrated measurements of the Earth's visible spectral albedos. Astrophys. J. 629, 1175–1182 (2005)

    Article  ADS  Google Scholar 

  10. Ehrenreich, D., Tinetti, G., Lecavelier Des Etangs, A., Vidal-Madjar, A. & Selsis, F. The transmission spectrum of Earth-size transiting planets. Astron. Astrophys. 448, 379–393 (2006)

    Article  CAS  ADS  Google Scholar 

  11. Miller-Ricci, E., Seager, S. & Sasselov, D. The atmospheric signatures of super-earths: How to distinguish between hydrogen-rich and hydrogen-poor atmospheres. Astrophys. J. 690, 1056–1067 (2009)

    Article  CAS  ADS  Google Scholar 

  12. Slipher, V. M. On the spectrum of the eclipsed Moon. Astron. Nachr. 199, 103 (1914)

    Article  ADS  Google Scholar 

  13. Moore, J. H. & Brigham, L. A. The spectrum of the eclipsed Moon. Publ. Astron. Soc. Pacif. 39, 223–226 (1927)

    Article  ADS  Google Scholar 

  14. Shane, C. D. Photographs of the lunar eclipse of June. Publ. Astron. Soc. Pacif. 39, 226–228 (1927)

    Article  ADS  Google Scholar 

  15. Sagan, C., Thompson, W. R., Carlson, R., Gurnett, D. & Hord, C. A search for life on Earth from the Galileo spacecraft. Nature 365, 715–718 (1993)

    Article  CAS  ADS  Google Scholar 

  16. Calo, J. & Narcisi, R. Van der Waals molecules — possible roles in the atmosphere. Geophys. Res. Lett. 7, 289–292 (1980)

    Article  CAS  ADS  Google Scholar 

  17. Klemperer, W. & Vaida, V. Molecular complexes in close and far away. Proc. Natl Acad. Sci. USA 103, 10584–10588 (2006)

    Article  CAS  ADS  Google Scholar 

  18. Solomon, S., Portmann, R. W., Sanders, R. W. & Daniel, J. S. Absorption of solar radiation by water vapor, oxygen, and related collision pairs in the Earth's atmosphere. J. Geophys. Res. 103 (D4). 3847–3858 (1998)

    Article  CAS  ADS  Google Scholar 

  19. Zbinden, P. A., Hidalgo, M. A., Eberhardt, P. & Geiss, J. Mass spectrometer measurements of the positive ion composition in the D- and E-regions of the ionosphere. Planet. Space Sci. 23, 1621–1642 (1975)

    Article  CAS  ADS  Google Scholar 

  20. Kopp, E. On the abundance of metal ions in the lower ionosphere. J. Geophys. Res. 102 (A5). 9667–9674 (1997)

    Article  CAS  ADS  Google Scholar 

  21. Gardner, J. P. et al. The James Webb Space Telescope. Space Sci. Rev. 123, 485–606 (2006)

    Article  ADS  Google Scholar 

  22. Charbonneau, D. & Deming, D. The dynamics-based approach to studying terrestrial exoplanets. Preprint at 〈〉 (2007)

  23. Kaltenegger, L. & Traub, W. A. Transits of Earth-like planets. Astrophys. J. (in the press); preprint at 〈〉 (2009)

  24. Woolf, N. J., Smith, P. S., Traub, W. A. & Jucks, K. W. The spectrum of earthshine: A pale blue dot observed from the ground. Astrophys. J. 574, 430–433 (2002)

    Article  CAS  ADS  Google Scholar 

  25. Montañés-Rodríguez, P. P., Palle, E. & Goode, P. R. Vegetation signature in the observed globally-integrated spectrum of Earth: modeling the red edge strength using simultaneous cloud data and applications for extrasolar planets. Astrophys. J. 651, 544–552 (2006)

    Article  ADS  Google Scholar 

  26. Turnbull, M. C. et al. Spectrum of a habitable world: Earthshine in the near-infrared. Astrophys. J. 644, 551–559 (2006)

    Article  CAS  ADS  Google Scholar 

  27. Palle, E., Goode, P. R., Montañés-Rodríguez, R. & Koonin, S. E. Changes in the Earth's reflectance over the past two decades. Science 304, 1299–1301 (2004)

    Article  CAS  ADS  Google Scholar 

  28. Cash, W. Detection of Earth-like planets around nearby stars using a petal-shaped occulter. Nature 442, 51–53 (2006)

    Article  CAS  ADS  Google Scholar 

  29. Lindensmith, C. Terrestrial planet finder: technology development plans. Optical, infrared, and millimeter space telescopes. Proc. SPIE 5487, 1226–1233 (2004)

    Article  ADS  Google Scholar 

  30. Palle, E., Ford, E. B., Seager, S., Montañés-Rodríguez, P. & Vázquez, M. Identifying the rotation rate and the presence of dynamic weather on extrasolar Earth-like planets from photometric observations. Astrophys. J. 676, 1319–1329 (2008)

    Article  ADS  Google Scholar 

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We thank F. Grundahl and J. Fynbo for allowing us access to their awarded time at the Nordic Optical Telescope, thus making this work possible. We are also grateful to V. J. S. Béjar, E. Guinan, S. Seager, B. Portmann, A. Garcia-Muñoz and Y. Pavlenko for discussions. Support for this project was provided by the Spanish Ministry of Science via the Ramon y Cajal fellowship (E.P.) and project AYA2007-67458. This work was based on observations made with the WHT (operated by the Isaac Newton Group) and the NOT (operated by Denmark, Finland, Iceland, Norway and Sweden), both on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

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Correspondence to Enric Pallé.

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Pallé, E., Osorio, M., Barrena, R. et al. Earth’s transmission spectrum from lunar eclipse observations. Nature 459, 814–816 (2009).

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