Daily Archives: March 1st, 2012

An Outsider’s Perception of Earth

Scientist’s claim that by using the Moon, they can determine that the Earth is habitable and thus, astrophysicists can find extrasolar Earth-like worlds:

Scientists looking at Earthshine reflected from the moon have concluded that, indeed, there is life on our planet. Though the result may be obvious, the findings can help in the search for life on other worlds.

This is not the first time that researchers have tried to see what the Earth would look like when viewed remotely. For example, the Voyager 1 spacecraft’s famous Pale Blue Dot image shows the Earth from nearly 4 billion miles away, giving a rough idea of what extraterrestrial telescopes looking at our planet would observe.

The recent study tried to get an outsider perspective from slightly closer to home. The sun’s rays hit the surface of the Earth and are reflected through the atmosphere. Most of that light escapes into the blackness of space but some of it bounces off the moon.

“Essentially, we use the moon as a giant mirror to look back at the Earth,” said astronomer Michael Sterzik of the European Southern Observatory in Chile, who co-authored the new paper out in Nature on Feb. 29.

This light contains a great deal of information. Break the light from a distant star into a spectrum and you can determine what elements are present.

One day, when scientists can directly detect light from an Earth-like planet, they may be able to check if its atmosphere contains things like oxygen, nitrogen, and methane. If present, these gases may represent biosignatures for distant life.

In addition to checking the Earthshine’s color, Sterzik and his team looked at the polarization, or direction, of the light waves bouncing off the moon. They were able to match the polarized light to different models, where our planet’s surface contained potential percentages of things like oceans, continents, and vegetation.

The model that best fit the polarized light contained a combination of these elements that looked exactly like, well, Earth. Though it may seem trivial at first glance, the finding has profound implications in the search for extraterrestrial life, said astronomer Darren Williams at Penn State Erie, The Behrend College, who was not involved with the study.

“It’s a demonstration that we have a fighting chance of learning what the surface of a distant planet is like,” he said.

Recently an “Earth-like” world was found ( https://dad2059.wordpress.com/2012/02/22/alien-planet-discovered-at-a-nice-safe-distance/ ) , but without a “Moon” to reflect light from.

Currently we do not have the technology to find a planet with moons. But the embattled James Webb Telescope would be capable of finding such planets.

Maybe by the end of this decade, we’ll have a list of actual Earth-type planets to study, either by stronger telescopes, advanced space probes or a combination of both.

I’m not betting on the space probes though.

Earth-shine helps in search for life on other worlds