Press Release

The search for ET just got easier

By SpaceRef Editor
June 10, 2009
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Astronomers using the Science and Technology Facilities Council’s (STFC) William Herschel Telescope (WHT) on La Palma have confirmed an effective way to search the atmospheres of planets for signs of life, vastly improving our chances of finding alien life outside our solar system.

The team from the Instituto de Astrofisica de Canarias (IAC) used the WHT and the Nordic Optical Telescope (NOT) to gather information about the chemical composition of the Earth’s atmosphere from sunlight that has passed through it. The research is published today (11th June) in Nature.

When a planet passes in front of its parent star, part of the starlight passes through the planet’s atmosphere and contains information about the constituents of the atmosphere, providing vital information about the planet itself. This is called a transmission spectrum and even though astronomers can’t use exactly the same method to look at the Earth’s atmosphere, they were able to gain a spectrum of our planet by observing light reflected from the Moon towards the Earth during a lunar eclipse. This is the first time the transmission spectrum of the Earth has been measured.

The spectrum not only contained signs of life but these signs were unmistakably strong. It also contained unexpected molecular bands and the signature of the earth ionosphere.

Enric Palle, lead author of the paper, from the Instituto de Astrofisica de Canarias, said, “Now we know what the transmission spectrum of a inhabited planet looks like, we have a much better idea of how to find and recognize Earth like planets outside our solar system where life may be thriving. The information in this spectrum shows us that this is a very effective way to gather information about the biological processes that may be taking place on a planet.”

Pilar Montanes-Rodriguez, from the Instituto de Astrofisica de Canarias, added, “Many discoveries of Earth-size planets are expected in the next decades and some will orbit in the habitable zone of their parent stars. Obtaining their atmospheric properties will be highly challenging; the greatest reward will happen when one of those planets shows a spectrum like that of our Earth.”

The past two decades have witnessed the discovery of hundreds of exoplanets (planets beyond our solar system). Ambitious missions, ground and space based, are already being planned for the next decades, and the discovery of Earth-like planets is only a matter of time. Once these planets are found, techniques like transmission spectra will be invaluable to their further exploration.

Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council (STFC), said, “This new transmission spectrum is good news for future upcoming ground and space based missions dedicated to the search for life in the Universe. The UK is committed to cutting edge science and UK owned facilities like the WHT are helping to make many groundbreaking discoveries and expand our knowledge of the Universe. Not only do these results improve our knowledge of our own planet but we now have an effective way to search for life on the increasing number of exoplanets being found by astronomers.”


Notes for editors


Images are available from the STFC Press Office or from the links below:

Image 1: An artist’s concept of the sunlight glowing through the Earth’s thin atmosphere and reaching an observer on the Moon during a lunar eclipse.

Credit: Gabriel Perez Diaz, SMM, Instituto de Astrofisica de Canarias (IAC)

Image 2: The Moon during a lunar eclipse. The red light illuminating the Moon’s surface during the eclipse has gone through the Earth’s atmosphere and carried the information of all the major Earth atmospheric components.

Image credit: Daniel Lopez, Instituto de Astrofisica de Canarias (IAC)


Julia Short
Press Officer
Tel: +44 (0)1793 442 012
Mobile: +44 (0)7770 276 721

Enric Palle
Instituto de Astrofisica de Canarias
Tel: +34 922 605268 or 670285955

Maria Rosa Zapatero
Instituto de Astrofisica de Canarias
Tel: +34 922 605389

Rafael Barrena
Instituto de Astrofisica de Canarias
Tel: +34 922605376

Eduardo Martin
Instituto de Astrofisica de Canarias
Tel: +34 922 605256

* The results on the WHT were achieved using LIRIS, a very efficient near-IR imager/spectrograph built and developed at IAC. LIRIS became a common-user instrument at the WHT as a result of the agreement signed by IAC to become a partner at ING in 2003.

* For a copy of the Nature paper ‘Earth’s transmission spectrum form lunar eclipse observations’ please contact the STFC Press Office.


The Isaac Newton Group of Telescopes (ING) is owned by the Science and Technology Facilities Council (STFC) of the United Kingdom, and it is operated jointly with the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) of the Netherlands and the Instituto de Astrofisica de Canarias (IAC) of Spain. The telescopes are located in the Spanish Observatorio del Roque de los Muchachos on La Palma, Canary Islands, which is operated by the Instituto de Astrofisica de Canarias (IAC).

Science and Technology Facilities Council

The Science and Technology Facilities Council ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange.

The Council has a broad science portfolio including Astronomy, Particle Physics, Particle Astrophysics, Nuclear Physics, Space Science, Synchrotron Radiation, Neutron Sources and High Power Lasers. In addition the Council manages and operates three internationally renowned laboratories:

* The Rutherford Appleton Laboratory, Oxfordshire * The Daresbury Laboratory, Cheshire * The UK Astronomy Technology Centre, Edinburgh

The Council gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Laboratory for Particle Physics (CERN), the Institute Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF), the European organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA). It also funds UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, and the MERLIN/VLBI National Facility, which includes the Lovell Telescope at Jodrell Bank Observatory.

The Council distributes public money from the Government to support scientific research.

The Council is a partner in the UK space programme, coordinated by the British National Space Centre.

SpaceRef staff editor.