Comet Catalina suggests comets delivering carbon to rocky planets

In early 2016, an icy visitor from the edge of our solar system rolled down the Earth. It briefly became visible to astronomers as Comet Catalina before passing in front of the Sun to disappear forever from the solar system.

Among the many observatories that captured a view of this comet, which appeared near the Big Dipper, was the Stratospheric Observatory for Infrared Astronomy (SOFIA), NASA’s telescope on an airplane. Using one of its unique infrared instruments, SOFIA was able to spot a familiar fingerprint in the dusty glow of the comet’s tail: carbon.

Now, this one-time visitor to our inner solar system helps explain our own origins further, as it becomes apparent that comets like Catalina could have been a critical source of carbon on planets like Earth and Mars during the solar system’s initial formation. .

New results from SOFIA, a joint project of NASA and the German Aerospace Center, have been published in the Planetary Science Journal.

“Carbon is the key to discovering the origins of life,” said lead author of the article, Charles “Chick” Woodward, astrophysicist and professor at the Minnesota Twin Cities Institute of Astrophysics. University of Minnesota. “We still don’t know if the Earth could have sequestered enough carbon on its own during its formation, so carbon-rich comets could have been an important source providing this essential element that led to life as we know it. “

Frozen in time

Coming from the Oort Cloud to the far reaches of our solar system, Comet Catalina and others of its type have orbits so long that they arrive at our Heavenly Gate relatively unchanged. This effectively makes them frozen in time, providing researchers with rare opportunities to learn more about the early solar system they came from.

SOFIA’s infrared observations were able to capture the composition of dust and gas as it evaporated from the comet, forming its tail. Observations showed that Comet Catalina is high in carbon, suggesting that it formed in the outer regions of the primordial solar system, which contained a reservoir of carbon that may have been important for the seeding of life. .

While carbon is a key ingredient in life, the early Earth and other terrestrial planets in the inner solar system were so hot during their formation that elements like carbon were lost or depleted. While cooler gas giants like Jupiter and Neptune could support carbon in the outer solar system, Jupiter’s giant size may have gravitatively blocked the carbon from mixing into the inner solar system.

Primordial mixture

So how did the rocky inner planets evolve into the carbon-rich worlds they are today?

Researchers believe that a slight change in Jupiter’s orbit allowed small comet precursors to mix carbon from outer regions into inner regions, where it was incorporated into planets like Earth and Mars.

The high carbon makeup of Comet Catalina helps explain how the planets that formed in the hot, low carbon regions of the early solar system evolved into planets with the supporting element of life.

“All terrestrial worlds are subject to the impacts of comets and other small bodies, which carry carbon and other elements,” said Woodward. “We are getting closer to the exact understanding of how these impacts on the early planets may have catalyzed life.”

Observation of additional new comets is needed to find out if there are many other carbon-rich comets in the Oort Cloud, which would further strengthen the fact that comets provide carbon and other vital elements to terrestrial planets. . As the largest airborne observatory in the world, SOFIA’s mobility allows it to quickly observe newly discovered comets as they pass through the solar system.