Astronomers found out how to look through the telescope of the green planet

SL, Вторник 25 Сентябрь 2018 - 13:12:20

Scientists have discovered how would have looked the Earth in different geological epochs, when you look at it from a cosmic distance. More specifically, they were interested in, which leaves a spectral trail of one or the other vegetation, from the first primitive mosses to a dense deciduous forest. This information, astronomers hope to use to search for habitable worlds.

Details of the research described in a scientific paper published in the journal Astrobiology Jack O Malley-James (Jack O'malley-James) and Lisa Kaltenegger (Lisa Kaltenegger) from Cornell University.

In 1990 the spacecraft Galileo sent to Jupiter and took pictures of the Earth from a relatively large distance. Scientists wanted to understand how the home of humanity looks for a remote observer. They found a kind of spectral "fingerprint" in the ultraviolet, visible and infrared range caused by the vegetation.

"The signal detected by Galileo for Earth, was similar to the one that can be observed from extrasolar planets in another solar system, but of course, Galileo was much closer to us," explains O Malley James.

Astronomical instruments quickly evolyutsioniruet and telescopes are preparing to launch in the coming years, will be aiming to consider the most interesting worlds. In this regard, it is interesting that they should see to the astronomers said, "yeah, there is also the vegetation!". Of course, the tool will not be able to directly see whether the planet is covered with forests.

To find out, the authors have modeled the spectra of a planet with earth's atmosphere and different vegetation. Aerial shell was divided into 60 thin layers with height from zero to hundred kilometers above the surface. Each of them was assigned their own parameters, absorption and reflection of electromagnetic waves. The spectrum was calculated for very high resolution: it was assumed that the receiver is able to distinguish parts with a width of 0.1 wave number.

The authors varied the area of the ocean, land, and vegetation in accordance with the geological era. For example, 475 million years ago, only 10% of the land was covered with greenery, and now 60%. Changed the composition of the vegetation. In the simulation, it was believed that in ancient era, up to 300 million years ago, the predominant type of plants were the mosses. Period 300-65 million years ago occurred in the dominance of ferns. After that they were replaced by gymnosperms and flowering plants.

The authors expected have concluded that the little "green" of the early Earth signal the presence of vegetation is negligible. Most impressive in this respect was the current era. When the simulation 70% of the planet's surface was considered to be the ocean, 2% of the coastline and 28% of the actual land. In turn, drying was 60% covered with vegetation, 9% granite, 9% basalt, 15% snow, and 7% sand.

However, the authors didn't just come to the conclusion that when a lot of vegetation, it can be clearly seen, and when a little something bad. They calculated the specific characteristics of the spectrum of our planet from different eras, which can serve as a reference for astronomers.

"We use the history of the Earth as the key to finding life in the Universe, sums up Kaltenegger. – Our work shows that as on Earth evolved plants signal the presence of vegetation (in these hypothetical telescope aimed at the Earth – approx. ed.) which shows their presence becomes stronger, which makes the ancient exoplanets really interesting places to search for vegetation."

Of course we can't know in advance how the biosphere of other planets. It is possible that it will have very little in common with the earth. But trying to check all possibilities would be like the anecdotal way to find a lion in the desert: it is necessary to sift the desert through a sieve, and the sieve will remain a lion. Searches lion more efficient to start from where it was last seen, and the search for life – worlds, like Earth. However, astronomers are not discounting much more exotic corners of the Universe.

We will remind that earlier "News.Science" ( wrote about how astronomers use different bodies of the Solar system as a model for the search of potentially habitable planets. We also talked about a comprehensive guide hunter of extraterrestrial life and artificial intelligence, having taken on this role.

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