In early 2016, an icy visitor from the edge of our solar system sped past Earth. It was briefly visible to stargazers like Comet Catalina before it passed the Sun to disappear forever out of the solar system.
Among the many observatories that captured a view of this comet, which appeared near Ursa Major, was the Stratospheric Observatory for Infrared Astronomy (SOFIA), NASA’s telescope on a plane. Using one of its unique infrared instruments, SOFIA was able to identify a familiar fingerprint within the dusty glow from the comet’s tail: carbon.
Now this unique visitor to our inner solar system is helping to explain more about our own origins, as it becomes clear that comets like Catalina could have been an essential source of carbon on planets like Earth and Mars during the early formation of the system. solar.
The new results from SOFIA, a joint project of NASA and the German Aerospace Center, were published in the Planetary Science Journal.
“Carbon is key to learning about the origins of life,” said lead author Charles “Chick” Woodward, an astrophysicist and professor at the University of Minnesota’s Twin Cities Minnesota Institute for Astrophysics. “We are still not sure if the Earth could have trapped enough carbon on its own during its formation, so carbon-rich comets could have been an important source of this essential element that led to life as we know it.”
Frozen in time
Originating from the Oort Cloud in the farthest reaches of our solar system, Comet Catalina and others of its kind have orbits so long that they reach our celestial threshold relatively unaltered. This effectively freezes them in time, offering researchers exceptional opportunities to learn about the early solar system from which they came.
SOFIA’s infrared observations were able to capture the composition of the dust and gas as it evaporated from the comet, forming its tail. The observations showed that Comet Catalina is rich in carbon, suggesting that it formed in the outer regions of the primordial solar system, which contained a deposit of carbon that could have been important for the seeding of life.
While carbon is a key ingredient of life, the early Earth and other terrestrial planets in the inner solar system were so hot during their formation that elements such as carbon were lost or depleted. While cooler gas giants like Jupiter and Neptune could support carbon in the outer solar system, Jupiter’s sheer size may have gravitationally locked the carbon out of re-mixing with the inner solar system.
So how did the rocky inner planets evolve into the carbon-rich worlds that they are today?
The researchers believe that a slight change in Jupiter’s orbit allowed the small early precursors of comets to mix carbon from the outer regions with the inner regions, where it was incorporated into planets such as Earth and Mars.
Comet Catalina’s carbon-rich composition helps explain how planets that formed in the warm, carbon-poor regions of the early solar system evolved into planets with the life-sustaining element.
“All terrestrial worlds are subject to impacts from comets and other small bodies, which carry carbon and other elements,” Woodward said. “We are getting closer to understanding exactly how these impacts on the first planets may have catalyzed life.”
Observations of additional new comets are needed to know if there are many other carbon-rich comets in the Oort Cloud, which would further support that comets delivered carbon and other life-sustaining elements to terrestrial planets. As the world’s largest aerial observatory, SOFIA’s mobility allows it to quickly observe newly discovered comets as they traverse the solar system.
Observations of a comet’s first pass through the solar system reveal unexpected secrets
Charles E. Woodward et al, The Coma Dust of Comet C / 2013 US10 (Catalina): A Window into Carbon in the Solar System, The Journal of Planetary Sciences (2021). DOI: 10.3847 / PSJ / abca3e
Provided by the University of Minnesota
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