As you’ve heard us say more than once, no one really understands the details of planet formation yet, and anyone who tells you they know exactly how planets form is either lying or on their way to a Nobel Prize. Part of the confusion comes from trying to separate what happens when the planets initially form and what happens later when those young planets get clobbered by countless asteroids and comets. 

We’re pretty sure that the early solar system had a gradient of materials, with different stuff being located in the inner and outer solar system. This matches what we see in the composition of asteroids from different locations and what we seem to see with planets and moons. The details aren’t clear, however, and every time a comet or asteroid comes close enough, we try to measure its composition if we can, and then question, “Did earth’s [water/nitrogen/whatever] form with the planet or come from collisions or both?”

Back in 2016, Comet 2013 Catalina passed near enough to earth for the SOFIA airborne observatory to look for specific elements in its tail and coma. In a new paper in The Planetary Science Journal with lead author Charles Woodward, researchers discuss observations of carbon – the base element of life – in the comet. According to Woodward: We’re still not sure if Earth could have trapped enough carbon on its own during its formation, so carbon-rich comets could have been an important source delivering this essential element that led to life as we know it. 

This particular comet originated in the Oort Cloud, far out beyond the observed planets, where more carbon may have been located. More observations of more comets are needed, but this is an interesting start. More and more it seems that our world required the heavy bombardment of comets and asteroids to make it (eventually) habitable to life.

More Information

University of Minnesota press release

“The Coma Dust of Comet C/2013 US10 (Catalina): A Window into Carbon in the Solar System,” Charles E. Woodward et al., 2021 February 8, The Planetary Science Journal