Earth’s sphere tilts on its axis at an angle of 23.5 degrees; this gives us our seasons, with parts of the planet receiving more direct sunlight in summer than in winter. However, not all solar system planets are tilted like the Earth: Uranus is tilted at 98 degrees, whereas Mercury is not tilted at all. According to new research led by Purdue University, a planet with a tilted axis helps to promote oxygen production by doubling the output of photosynthesis.
Exoplanets which are tilted on their axis, like Earth, are more capable of evolving complex life. Image credit: Sci-News.com.
“There are several factors to consider in looking for life on another planet,” said lead author Dr. Stephanie Olson, a planetary scientist in the Department of Earth, Atmospheric, and Planetary Science at Purdue University.
“The planet needs to be the right distance from its star to allow liquid water and have the chemical ingredients for the origin of life.”
“But not all oceans will be great hosts for life as we know it, and an even smaller subset will have suitable habitats for life to progress towards animal-grade complexity.”
“Small tilts or extreme seasonality on planets with Uranus-like tilts may limit the proliferation of life, but modest tilt of a planet on its axis may increase the likelihood that it develops oxygenated atmospheres that could serve as beacons of microbial life and fuel the metabolisms of large organisms.”
“The bottom line is that worlds that are modestly tilted on their axes may be more likely to evolve complex life.”
“This helps us narrow the search for complex, perhaps even intelligent life in the Universe.”
In the study, Dr. Olson and colleagues produced a sophisticated model of the conditions required for life on Earth to be able to produce oxygen
The model allowed the team to input different parameters, to show how changing conditions on a planet might change the amount of oxygen produced by photosynthetic life.
“The model allows us to change things such as day length, the amount of atmosphere, or the distribution of land to see how marine environments and the oxygen-producing life in the oceans respond,” Dr. Olson said.
The researchers found that increasing day length, higher surface pressure, and the emergence of continents all influence ocean circulation patterns and associated nutrient transport in ways that may increase oxygen production.
They believe that these relationships may have contributed to Earth’s oxygenation by favoring oxygen transfer to the atmosphere as Earth’s rotation has slowed, its continents have grown, and surface pressure has increased through time.
“The most interesting result came when we modeled ‘orbital obliquity’ — in other words how the planet tilts as it circles around its star,” said Megan Barnett, a Ph.D. student in the Department of Geophysical Sciences at the University of Chicago.
“Greater tilting increased photosynthetic oxygen production in the ocean in our model, in part by increasing the efficiency with which biological ingredients are recycled.”
“The effect was similar to doubling the amount of nutrients that sustain life.”
The scientists presented their findings this week at the 2021 Goldschmidt Geochemistry Conference.
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Stephanie Olson et al. Ocean Dynamics and the Oxygenation of Habitable Worlds. Goldschmidt 2021, paper # 7332
http://www.sci-news.com/space/modestly-tilted-planets-complex-life-09842.html
2021-07-08 20:05:24Z
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