A new technique enables scientists to search for traces of life on exoplanets in reflected light

A new approach to searching for life on other planets: An international team has discovered that biopigments of plants, so-called biological photosynthetic pigments, leave behind unique traces in the light they reflect. Prof. Dr. Svetlana Berdyugina from the Institute of Physics of the University of Freiburg and the Freiburg Kiepenheuer Institute for Solar Physics studied these biosignatures together with researchers from the University of Hawaii at Manoa, USA, and the University of Aarhus, Denmark, with the help of polarization filters: If biopigments were present as a sign of life on a planet, they would leave behind a detectable polarized signature in the reflected light. The scientists have now published their findings in the International Journal of Astrobiology.

Photosynthetic pigments are plant substances that absorb and reflect particular wavelengths of visible light, making them appear in color in the reflected wave ranges. Biopigments are what gives plants, algae, bacteria, and human skin and eyes their colorful appearance. Chlorophyll pigments in plant leaves, for instance, absorb blue to red light but reflect a small part of green in the visible spectrum and thus appear green. An exception is infrared light: half of it is reflected and the other half passes through the leaf. Carotenoids absorb blue and red light but reflect yellow light and are thus typically red, orange, or yellow in color.

The scientists discovered that the part of the visible light spectrum reflected in colors by various plants oscillates in particular directions, meaning that it becomes polarized. Each biopigment leaves behind a colorful footprint in the polarized light. The researchers can detect this biosignature with the help of polarization filters, which function similarly to polarized sunglasses or 3D movie glasses. The signature in the polarized light of plants on distant planets would also be detectable in this way. The high contrast of the biosignatures in the polarized light could be the key for finding them in overwhelmingly bright stellar light that hides exoplanetary signals.


"This technique could be instrumental in searching for life in Alpha Centauri, the planetary system closest to the Sun," says Berdyugina. The astrophysicist points out that the star Alpha Centauri B is optimal for searches with current telescopes because it is one of the closest to the Earth. No planet has yet been found in Alpha Centauri B's habitable zone - the distance from a central star at which a planet can have liquid water on its surface, the precondition for life as we know it on Earth.
"Even before such a planet is found, we can use the polarization technique to search for biosignatures that point to life," says Berdyugina. Larger telescopes will be needed to examine more distant planetary systems. Until astronomers build such telescopes, the team aims to search for photosynthetic footprints in the light of the Alpha Centauri system.

This video shows an imaginary journey from Earth to the Alpha Centauri system. As we leave the Solar System we see the familiar constellation figures including the Southern Cross (Crux) and the bright stars Alpha and Beta Centauri. As we approach Alpha Centauri we pass a faint red star, this is Proxima Centauri, the closest star to Earth and the faintest component of a triple star system. The final part shows the bright double star Alpha Centauri A and B with the Sun visible in the background. Alpha Centauri B is known to be orbited by an Earth-mass planet, the closest exoplanet to the Solar System.
Credit: ESO./L. Calçada/Nick Risinger (skysurvey.org).


Contacts and sources:
Albert-Ludwigs-Universität Freiburg

Citation: Svetlana V. Berdyugina, Jeff R. Kuhn, David M. Harrington, Tina Šantl-Temkiv and E. John Messersmith. "Remote sensing of life: Polarimetric signatures of photosynthetic pigments as sensitive biomarkers." International Journal of Astrobiology. doi:10.1017/S1473550415000129.http://dx.doi.org/10.1017/S1473550415000129

and just what would the leaders of planet earth do,, if life was found on other planets.
we cant look after the people on this planet,
people on this planet are dying for lack of food and water
people are slaying people
race killing race
religion killing religion
and people are wondering about mars and other planets. woooooooow
we really are ****ed up

would? they already have, and they hide it from us... Roswell wasn't a weather balloon...

about 7-8 alien crafts have crashed on earth, that i've heard of... one in Aurora, Texas, in the 1880's, mexico in the 70's, 2 in Canada, and 2 in Russia...

but this article is about finding simple life - bacterias, plants and plankton's..

You raise an interesting point. If we found life on distant planets, would we instantly offer them food stamps?

If we met intelligent life on distant planets, would they use their intelligence to tell us to use birth control?

There are 'No Leaders' in other planets.
Why do we constantly forget humans are the most intelligent & complex & even if there is A.L.F out there it won't be smarter then a human....


However if you end up on a distant Planet & are put in a dungeon by it's leader's do not blame me

an ethnocentric view for certain...

Yeah coz humans are the most superior of creations....in everyway ...

I'll bet pork tastes better!

not sure... do the liberals need their votes?

While Humans try to find life on other planets, we Melmacians are still trying to find intelligent life that is indigenous to planet Earth.