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Earth’s chemical fingerprint could help identify habitable exoplanets

29 Aug 2019, 06:00 UTC
Earth’s chemical fingerprint could help identify habitable exoplanets
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An artist’s impression of Earth-like planets. Image: NASA/ESA/G. Bacon (STScI)
Canadian astronomers at McGill University, using satellite data collected over the past decade, have come up with a spectral “fingerprint” of Earth that could be compared to atmospheric signatures from exoplanet transits to help determine their ability to support life.
The infrared transit spectrum shows the presence of key molecules in Earth’s atmosphere that presumably would be present in any viable biosphere, including the simultaneous presence of ozone and methane, which would only be expected from organic sources.
“A handful of researchers have tried to simulate Earth’s transit spectrum, but this is the first empirical infrared transit spectrum of Earth,” said Nicolas Cowan, who supervised the research carried out by McGill physics student Evelyn Macdonald. “This is what alien astronomers would see if they observed a transit of Earth.”
The study was published in the journal Monthly Notices of the Royal Astronomical Society. It was based on data from the Canadian Space Agency’s SCISAT, a satellite built to study Earth’s ozone layer by monitoring how sunlight passing through the atmosphere is affected by the suspended particles it passes through.
Transiting exoplanets pass in front of their host stars as viewed ...

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