Comet 3I/ATLAS is just the third interstellar comet that humans have ever detected coming into our solar system, so that alone makes it very rare. Being able to get an ‘up close’ look at objects coming from outside of our solar system gives astronomers a lot of new data to use.

Even for such a rare event, however, this comet has a lot to make it unique. For one, it is quite large and oddly shaped. In addition, it is traveling extremely fast, which has led many people to wonder if it was made (or maybe even occupied) by an intelligent lifeform.

So, when the James Webb Space Telescope (JWST) had the opportunity to get pointed toward the comet, everyone was excited. The JWST ‘looked’ at the comet for just 10 minutes, but it used the infrared eye instruments to get as much valuable information as possible.

What astronomers learned was that it was outgassing carbon dioxide at a rate higher than all but just one comets ever observed. The team analyzing the results of this observation submitted a study to the Astrophysical Journal Letters, which is available on ArXiv. Dr. Martin Cordiner is the lead author on the study, and when asked about the research by IFLScience, he said:

“We observed an interstellar space rock with JWST! The data are spectacular, and considering the short (10-minute) observing time, the amount of information we got is astounding.”

Another unusual thing that they found is that it has sunward outgassing, meaning that the coma (the area around the comet) is mostly CO2, but it is coming off toward the sun rather than away from it. Dr. Cordiner went on to say:

“3I/ATLAS is different compared to our usual comets. It is releasing so much CO₂, it’s the second most CO₂-rich comet ever seen, after the “peculiar” outlier R2/PAnSTARRS. This makes it one of the most unusual comets ever seen. Having said that, it also has a lot of spectral features in common with normal comets – ice, gas, and dust.  So from one perspective, considering its alien nature, it’s surprisingly similar to our own comets, yet it has this surprisingly high CO₂ abundance, which means it must be fundamentally different in some way.”

The team that worked on the paper proposes that the difference comes at the nucleus of the comet, and that it is enriched with carbon dioxide. They do not have any solid answers as to how that enrichment occurred, but they do give some possibilities. Dr. Cordiner explains:

“Regarding the origin of all that CO₂, it seems that irradiation of ices in space can convert CO [carbon monoxide] + H₂O [water] to CO₂, so the question is, when did that happen? Was it during the object’s formation (perhaps in a disk around a star that was producing a lot of UV and X-rays), or did it happen during the object’s subsequent interstellar voyage (for instance, if it passed close to the galactic center, or flew by a supernova)? I don’t have enough information to answer that right now, but with more observations (and theoretical studies), hopefully we can start to build up a clearer picture.”

However it occurred, this is a very unusual comet and it will give scientists a lot of data to study. The comet is still traveling in the general direction of Earth and in late October, it will reach its closest point, which will still be 210 million kilometers (130 miles) from the sun and well outside the Earth’s orbit.

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