Imaging suggests that a lot of the material coming off is in the form of dust grains. NASA indicated that two missions to asteroids, Lucy and Psyche, were especially helpful here, since they were farther from the Sun than 3I/ATLAS, and so could capture backlit images of the comet’s coma.

NASA’s Tom Statler, the lead scientist for Solar System bodies, said that the amount of material being released by 3I/ATLAS is fairly typical of Solar System comets. But some of the details are a bit unusual. For example, the ratio of carbon dioxide to water being released is higher than we see from local comets. Those normally emit iron and nickel together, but 3I/ATLAS seems to be unusually nickel-rich. So, there are indications that it has a history that differs somewhat from our Solar System’s comets.

That history is tough to discern. 3I/ATLAS came from the direction of the galactic core, and doesn’t appear likely to have interacted with any other stars recently. If that’s right, then it’s possible that the object is older than the Solar System itself, and came from a star that formed relatively early in the Universe’s history, and thus had far fewer of the heavy elements.

For now, NASA has put up a webpage with a large collection of images of 3I/ATLAS and will update the site as more photos become available. But the scientists on the call today emphasized that it’s still very early going in terms of analysis, and some of these ideas may be refined as they make their way through discussions among scientists and peer review at journals.

Fox also made it clear that we were able to quickly spot and characterize the orbit of 3I/ATLAS partly because we’ve set up systems to identify any Earth-threatening objects as part of our planetary defense program. With that and other automated surveys in place, it’s likely that the three objects we’ve seen so far (two comets, one asteroid) will gradually be joined by others, and we’ll be able to build up a clearer picture of what’s floating out among the stars.