Another finding was that the ratio of two types of carbon isotopes, Carbon-12 and Carbon-13, was broadly similar to that found on Earth, suggesting the material was created in an environment with similar carbon species. However, there are a couple of features of 3I/ATLAS’s creation that could have caused the lopsided CO2/H2O ratio.

One is extremely high levels of ultraviolet radiation in the host star system the object was created it. Another could be that is was created beyond the CO2 “ice line”, where carbon dioxide ice is relatively abundant compared to water. Other explanations have to do with how heat from the Sun is able to affect the nucleus - if it is harder to heat up, then CO2, which has a lower melting point than water, would be sublimated first, accounting for the lopsided ratio despite having plenty of water stored in the nucleus waiting to be released as it gets closer to the Sun.

Either way, more observations are needed.