The search for extraterrestrial life is no longer the prerogative of science fiction or UFO hunters. Modern technologies may not have yet reached the required level. Yet they have already enabled us to detect physical and chemical manifestations of the fundamental processes at the core of all living things. Astronomers have discovered over 200 planets revolving around starts outside our solar system. So far we are unable to answer with certainty the question about the probability of life on these planets, but this is only a matter of time. In July 2007, after analyzing start light passing through the atmosphere of an extrasolar planet (or exoplanet), astronomers confirmed the presence of water on the planet. Scientists are already developing telescopes capable of searching for traces of life on planets similar to Earth using their spectrums.
One of the key factors influencing the spectrum of light reflected by a planet can be photosynthesis. But is this possible in other worlds? Absolutely! On Earth, photosynthesis is the foundation of practically all living things. Even though some organisms have developed the ability to live at high temperatures in a methane environment and in hydrothermal oceanic springs, it is to solar light that we owe the variety of ecosystems on the surface of the Earth.
On the one hand, photosynthesis results in the production of oxygen which can be detected in the planet’s atmosphere along with ozone that is produced with it. On the other hand, the planet’s color can indicate the presence of special pigments, such as chlorophyll, on its surface. Almost a century ago, upon noticing the seasonal darkening of the Martian surface, astronomers suspected it may have vegetation. Attempts were made to detect signs of green plants in the spectrum of light reflected off the planet surface. Yet the questionable nature of this approach was pointed out even by the writer Herbert Wells, who pointed out in his book, War of the Worlds: “Obviously, the plant kingdom of Mars, unlike terrestrial with its predomination of green color, is colored bloody red”. Now we know that Mars has no vegetation and that the appearance of darker areas on its surface is due to sandstorms. Well himself was confident that the color of Mars was in many ways due to the plants covering its surface.