Since the discovery of the first exoplanet in 1992, scientists have believed that a planet must possess several components to support life, such as being in the “Goldilocks zone” of its host star for the existence of liquid water, having water, and oxygen in its atmosphere.
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Planets with tilts like Earth are likely to have life. Image: NASA
Researchers have created models to understand the necessary conditions for the survival and development of life on Earth, focusing on how variations in factors such as the amount of oxygen produced through photosynthesis affect those conditions.
“Our model allows us to change things like the length of the day, the atmospheric composition, or the distribution of land to see how the marine environment and oxygen production in the ocean react,” said Stephanie Olson, the lead researcher from Purdue University, USA.
There are three factors that can increase the oxygen level on a planet: a longer day, higher surface pressure, and the formation of continents through plate tectonics.
All these input factors can significantly influence the oceanic biogeochemical cycles and related nutrient distribution.
When modeling the “axial tilt” or how exoplanets tilt as they orbit their host star, the research team found that a larger tilt can enhance oxygen production in the oceans.
Earth has a tilt of 23.5 degrees, while Mars tilts at 177.3 degrees and Venus at 25.2 degrees. Mercury, Jupiter, Saturn, and Neptune have different tilts, which are 3.1 degrees, 26.7 degrees, 97.8 degrees, and 28.3 degrees respectively, according to NASA.
The modest tilt like that of Earth can “enhance the ability (of a planet) to develop an oxygen-rich atmosphere, which serves as a biosignature for the presence of microbial life and provides energy for the metabolism of larger organisms,” emphasized the research team.
According to the researchers, this helps narrow down the search for complex, potentially intelligent life in the universe.
The study was presented at the Goldschmidt Geochemistry Conference 2021.
To date, over 4,700 exoplanets have been confirmed in more than 3,500 planetary systems detected by humans, including nearly 800 systems with more than one planet.