The weather and surface conditions of planets outside our Solar System could be detected by constellations of telescopes sent to space, and then used to predict which are most Earthly and likely to harbor life, according to new research.
Eric Ford of Princeton University Observatory and his colleagues developed computer code to calculate the total light scattered by an extrasolar planet toward an observer.
Their model predicts that the light scattered by such planets can be interpreted to indicate the ratio of ocean to land mass on a planet, its cloud cover, the presence of ice and possibly the presence of plant life and other biology.
High-end telescopes that could do the job of detecting that light currently are in the planning stages at NASA (
The team's work was published in this week's issue of the journal Nature.
Weather reports from afar
To make their calculations for extrasolar planet detection, Ford and his colleagues studied Earth's reflectivity as it would appear if it were observed from a distant star -- the kind of observation TPF or Darwin would make in reverse, according to New Scientist magazine.
The team figured out the variables that alter Earth's reflectivity from that distance, including whether an ocean is facing the observer and the local weather.
"If you were an alien observer, looking at Earth from somewhere else in the galaxy, just by checking how bright Earth is as it rotates, not only could you determine the Earth's rotation period and that it has land and oceans, but you could also detect our changing cloud patterns," Ford told New Scientist.
Seasonal cloud cover can cause up to a 20 percent variation in Earth's reflectivity, the team found.
The hope is that the team's calculus for planetary reflectivity could be used to decide which planets to study for signs of life once the celestial objects themselves were found. For instance, a Venus-like planet, shrouded in clouds would reflect a constant amount of light whereas an Earth-like planet's shine would vary, Ford told the magazine.
Ford and his colleagues recommend that mission planners for TPF and Darwin include photometers, or sophisticated, highly sensitive light sensors, aboard their multi-telescope missions that could perform rapid reflectivity analyses of planets and save time in selecting which planets to study more closely for more definitive indicators of life.
advertisement
