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New NASA-funded research suggests that planets orbiting their stars on a tilted axis are more likely to have atmospheric oxygen.

According to the hypothesis, liquid water can persist on the surface of a planet in a "Goldilocks zone" that is neither too hot nor too cold. Experts believe this is another critical ingredient in life as we know it.

"Worlds that are modestly tilted on their axes may be more likely to evolve complex life," Stephanie Olson from Purdue University and lead researcher of the study presented at the Goldschmidt Geochemistry Conference. "This helps us narrow the search for complex, perhaps even intelligent life in the Universe," Olson added.

An artist's interpretation of the exoplanet Proxima b
(Photo: ESO/M. Kornmesser via Wikimedia Commons)
This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

The findings come from a sophisticated model of the conditions required for life on Earth to manufacture oxygen, which could help scientists hone NASA's quest for more advanced life on distant exoplanets.

Because oxygen is required for respiration, the chemical activity that drives the metabolisms of most complex living forms, such as plants and animals, is fundamental to life.

The researchers used the model to assess how changing environmental conditions on a planet could affect the amount of oxygen produced by photosynthetic life. It comes on the heels of a report published by Forbes that looked at photosynthesis and suggested that Earth-like conditions on possibly habitable planets may be far more common than previously imagined.

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The researchers discovered that as the Earth's rotation slowed and the number of days lengthened. Experts, per Space Daily, attributed it to its tilt, continents developed, the surface pressure increased, and ocean circulation patterns changed, potentially increasing oxygen generation.

Megan Barnett, a doctoral student at the University of Chicago who was not part of the study, said the researchers came up with the most interesting conclusion came when they modeled orbital obliquity.

Barnett explained that the model, more tilting boosted photosynthetic oxygen production in the ocean, partly through boosting the efficiency with which biological materials are recycled. It seemed as if the number of nutrients needed to support life had been doubled.

Olson said small tilts or extreme seasonality might hinder the expansion of life on planets with Uranus-like tilts. Uranus is virtually on its side, with a tilt of almost 98 degrees. However, she explained that the slight tilt of a planet's axis might boost the chances of the planet's developing oxygenated atmospheres. The factor might act as beacons for microbial life and feed the metabolisms of massive organisms.

What is the bottom line? Though exoplanet researchers are thrilled about the possibility of studying extraterrestrial atmospheres with the future James Webb Space Telescope (JWST), its findings could be misleading. In fact, worlds that are tilted on their axes may have a higher chance of developing complex life.

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