Comet Carbon Monoxide Concentrations

The bottom axis of this graph shows the range of carbon monoxide concentrations (or amount of carbon monoxide relative to the amount of hydrogen cyanide) among solar system comets. The unusually high concentration detected in 2I/Borisov, the first interstellar comet, is highlighted in red. The comet shown on the far right is C/2016 R2 (PanSTARRS), presumably, a solar system comet with CO levels estimated to be dozens of times higher than Borisov’s. Credit: NASA Goddard/Martin Cordiner/James Tralie