Scientists have named the easiest way to find alien life
In order to find distant planets that could potentially host extraterrestrial life, scientists must look for celestial bodies whose atmosphere resembles that of the Earth, but from the distant past. We are talking about unusually high levels of oxygen, ozone, and methane.
This is stated in a study by Cornell University astronomers Lisa Kaltenegger and Rebecca Payne, published in the journal Monthly Notices of the Royal Astronomical Society.
In their study, Kaltenegger and Payne used climate models and geological data to figure out how much oxygen and other gases the Earth's atmosphere contained at important moments over the past 500 million years. They then modeled what such an Earth would have looked like from the past if its transit of the Sun had been observed by astronomers on distant worlds.
The transit method is used by Earth scientists to study exoplanets. It involves observing a planet while it is passing between the Earth and its star. During this period, the cosmic body blocks the light of the star, but part of this light passes through a thin layer of atmosphere at the edges of the planet. Due to the fact that various compounds in the atmosphere will have their own chemical fingerprint (in other words, color), which will be highlighted by the star's shine, scientists can study what gases the observed planet contains.
The idea of the Cornell University astronomers is that the more a particular gas is in the atmosphere, the better we will be able to see it. For example, when the first dinosaurs appeared on Earth, the level of oxygen in the atmosphere was at an all-time high and was estimated to be 30 to 35 percent of the atmosphere (now it is about 21 percent).
Therefore, according to Payne, for distant observers, the Earth could look like an even more developed and life-rich planet only because there was so much oxygen in the atmosphere.
At the same time, oxygen alone is not proof that life exists on a planet, or that it is at least habitable. However, if a planet has a lot of oxygen in its atmosphere, it is worth studying better.
It will be important to find the combination of oxygen and methane, as both chemicals are produced by living things, geological processes, and chemical reactions in the upper atmosphere. Another important clarification is that methane and oxygen do not like to coexist for very long. In particular, on Earth, ultraviolet radiation causes them to mix, forming carbon dioxide and hydrogen.
Therefore, if they are present in the planet's atmosphere in significant quantities, it probably means that there is some source on the surface that is able to constantly replenish their reserves. Such a source could be breathing living things.
Payne believes that most astrobiologists would consider "the presence of large amounts of oxygen and ozone and at least a stable but smaller amount of methane" as convincing evidence of life on the planet.
If there are also conditions for the existence of water, it would mean that "this place is really worth looking at."
Payne also explained that the search for Earth-like planets from the past is not only easier because the planets are easier to recognize, but it also makes sense because scientists will be able to get a general idea of what this world will be like in the future.
Earlier, OBOZ.UA told that, according to one of the theories of scientists, aliens may be so different from humans that they will not even realize that people are living beings.