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| A new technique for detecting signs of life on distant planets by analyzing reflected light could soon lead astronomers to extra-terrestrial life.
According to a report in the Telegraph, when scientists tested the method on Earth, they found unmistakably strong signs of life in the form of chemical "fingerprints". They believe within one or two decades the same technique could reveal life on worlds orbiting stars far beyond the Sun. Reflected light was already known to contain valuable information about a planet's atmosphere. But, at distances of many light years the signals, from light wavelength patterns called spectra, are very faint and difficult to read. The new technique takes a different approach by studying light passing through the atmospheric layer instead of reflected off it. This kind of light pattern, known as a "transmission spectrum", was found to provide a much stronger signal. Analyzing the light can reveal biologically important chemicals such as oxygen and water, which indicate the presence of life. The test was carried out during a lunar eclipse by observing moonlight passing through the Earth's atmosphere. This was equivalent to observing the Earth's spectrum from far away as the planet passed in front of the Sun. The astronomers used the UK-run William Herschel Telescope (WHT) on La Palma in the Canary Islands. "Now we know what the transmission spectrum of a inhabited planet looks like, we have a much better idea of how to find and recognise Earth-like planets outside our solar system where life may be thriving," according to Dr Enric Palle, from the Astrophysics Institute of the Canaries, who led the research. "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," he said. "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," said Dr Pilar Montanes-Rodriguez, from the Astrophysics Institute of the Canaries. According to Professor Keith Mason, chief executive of the Science and Technology Facilities Council (STFC) which funds the William Herschel Telescope, "This new transmission spectrum is good news for future upcoming ground and space-based missions dedicated to the search for life in the universe." |
