Experts from NASA and ESA conducted an unusual experiment to test a new criterion for searching for exoplanets. We cannot spend efforts on searching and studying all planets from other worlds, we are primarily interested in habitable or suitable for life. One of the conditions for this is the presence of an atmosphere with a certain composition of gases, so astronomers decided to learn how to look for this sign.
At this scientific and technical stage, all the information that we can get from a distant exoplanet is represented by light. Telescopes detect changes in it, scientists analyze and interpret the data. There are many different qualitative algorithms for these purposes, but the search for the atmosphere through the study of light coming from the planet itself has not previously been carried out. Fortunately, we were helped by the presence of the Earth itself and the atmosphere, and a satellite in the form of the Moon, which helped to study this light.
The idea was to capture the light that passed through the Earth's atmosphere, which reached the moon and was reflected into space. There he was caught by the Hubble Space Telescope, specially deployed for this mission. Scientists are well aware of almost all the parameters of the equation: the composition of the earth's atmosphere, the initial parameters of the light source, the characteristics of the "mirror", and now they have received data from the telescope. It remains to collect all the information together, to deduce patterns so that in the future, in the light of exoplanets, you can immediately understand whether there is a comfortable atmosphere for life there or not.
Ozone was chosen as the main element of the search. First, ozone is obtained from oxygen, and this is an important criterion for the possibility of life on the planet. Second, ozone helps protect the planet from dangerous ultraviolet radiation, which also greatly increases the chances of the birth of life on it. Now scientists have at their disposal ozone signatures for the Earth's atmosphere, with which distant exoplanets will be compared.