'Surprising' chemistry of interstellar comet could offer insight into distant planets

Comet which travelled from outside solar system has fascinated scientists

The Hubble Space Telescope captured this image of the comet 31/Atlas when it was 445,787km from Earth on July 25. Photo: Hubble Space Telescope / Nasa

An interstellar comet passing through the solar system contains a surprising mix of chemicals, findings that could help researchers learn more about how planets and stars form elsewhere in the galaxy.

Comet 3I/ATLAS is the third confirmed object from outside the solar system that was discovered in July by a Nasa-funded telescope in Chile, following the discovery of ʻOumuamua in 2017 and 2I/Borisov in 2019.

Astronomers have been able to photograph and analyse 3I/ATLAS’s composition in greater detail, thanks to follow up observations by Hubble Space Telescope and the James Webb Space Telescope.

Dr Richard Leveille, a planetary scientist at McGill University in Canada, said the comet’s chemical make-up is different to those found in the solar system.

“For example, it appears to have abundant nickel, but not much iron,” Dr Leveille told The National, who is also a participating scientist at Nasa.

“This is a bit surprising as these two elements are often found together, such as in cores of rocky planets or metallic meteorites.

“Perhaps more surprisingly, it is much enriched in carbon dioxide compared to water. Again, this is different from comets in our solar system that have more water than CO2.”

He said scientists are still unsure of what these differences mean, and the results are preliminary.

But it could be that they indicate the planetary-star system where the comet originates from is “so different” to ours that it leads to this unusual chemical composition.

Dr Dimitra Atri, principal investigator at NYU Abu Dhabi’s space exploration laboratory, said researchers often study comets closer to home because they could reveal clues of the early Solar System.

“These bodies preserve records of early solar system processes erased on Earth by tectonic activity and weathering,” he told The National.

“Asteroids and comets, remnants of the solar system’s formation, contain pristine materials that likely delivered water and organics to Earth.

“Analysing them helps reconstruct early Earth conditions and informs predictive climate models, including potential geoengineering solutions.”

Researchers now have a rare opportunity to study comets like 3I/ATLAS that could reveal more details on other star systems.

Dr Leveille said more information about the composition of the comet could help scientists compare the solar system to other ones in the galaxy.

“More detailed analyses and study of this comet, along with studies of other interstellar comets, will no doubt tell us about the diversity of planetary systems and the ranges of conditions that can be found beyond our solar system,” he said.

“Already, studies of exoplanets are showing us that our solar system is different in many ways from many other planetary systems.”

'Oumuamua, the first known object from interstellar space, was discovered travelling through the solar system in 2017. This image is an artist's impression. Photo: Nasa

Some planetary systems, for example, orbit two or more stars, unlike our solar system which has only one, the Sun.

This means planets there experience very different conditions from what we see on Earth.

Dr Leveille said improvements in technologies and “a bit of luck” are helping to spot these objects as they are very far from Earth.

“Future observatories will likely find more of them. The new Vera Rubin Observatory is predicted to find several interstellar object every year of its operation,” he said.

“The more interstellar objects we find and study, the more we will be able to say about the origins and evolution of our own solar system and be able to assess the diversity of planetary systems elsewhere in our galaxy.

“How unique is our solar system? What does it take for planets to be habitable? How does that relate to the possibility of life elsewhere? With more discoveries of interstellar objects, we will be closer to answer these questions.”