MIT, University of Birmingham, etc.
Research results have shown that it is possible to determine whether life exists on a planet outside the solar system by analyzing the amount of carbon dioxide in its atmosphere. Provided by Getty Image Bank
Research has shown that the presence of life on a planet can be determined by checking the presence or absence of carbon in the atmosphere.
A joint research team including the Woods Hole Oceanographic Institution at the Massachusetts Institute of Technology (MIT) and the University of Birmingham in the UK found that if the percentage of carbon dioxide contained in the atmosphere of a terrestrial planet is lower than that of other planets in the same planetary system, it could be a sign that liquid water exists on the surface of that planet. A paper was published in the international academic journal ‘Nature Astronomy’ on the 28th (local time) stating that the existence of life can be inferred through this.
To date, about 5,200 planets beyond the solar system have been discovered, but the data obtained through telescopes has limitations in determining whether the planets have an environment in which life can thrive. If there is liquid water on the planet’s surface, there is a high probability that life exists, but it is difficult to observe it directly.
In the case of planets in the solar system, the presence of liquid is determined through intense flashes (glints) as the liquid on the planet’s surface reflects sunlight. For example, a kind of ‘reflected light’ was observed on Titan, Saturn’s largest moon, and through this, it was confirmed that a huge lake exists on Titan.
However, with current technology, it is difficult to detect similar light on planets far outside the solar system. Instead, the research team explained that if it is a ‘terrestrial planet’, the presence or absence of liquid on the planet’s surface can be determined by analyzing the amount of carbon dioxide in the atmosphere.
A terrestrial planet is a planet composed mainly of heavy elements such as iron or siliceous rocks. Unlike Jupiter-type planets, which are mainly composed of hydrogen and helium, it has a hard surface. Earth, Venus, and Mars are representative terrestrial planets.
The research team focused on characteristics that only Earth has, unlike Venus and Mars. Compared to Venus and Mars, Earth has significantly less carbon dioxide in the atmosphere.
Amery Trio, a researcher at the University of Birmingham in the UK who led the study, said, “Assuming that Earth, Venus and Mars were created in a similar way, the fact that Earth’s carbon dioxide is significantly less than that of other planets means that the carbon was removed by some other factor.” He cited the ‘ocean’, which absorbs carbon dioxide from the atmosphere and regulates the concentration of carbon dioxide in the atmosphere, as the factor.
In fact, the ocean has played a major role in absorbing carbon dioxide generated on Earth. It is known that the ocean has absorbed an amount similar to the amount currently remaining in the atmosphere of Venus over hundreds of millions of years. The explanation is that through this cycle, the amount of carbon dioxide distributed in the Earth’s atmosphere has decreased compared to neighboring planets.
The research team stated that if a planet outside the solar system can detect ‘depletion’ of carbon dioxide in the atmosphere similar to the Earth environment, it serves as a signal that liquid water exists on that planet and that life may exist.
The research team explained, “Carbon dioxide is a very strong absorber in the infrared range and can be easily detected in the atmosphere of an exoplanet. Through the carbon dioxide signal, we will be able to reveal whether liquid exists on an exoplanet.”
