Interstellar comet 3I/ATLAS found to be older than the solar system

Scientists studying the comet 3I/ATLAS have found that it is older than our solar system. The study, published on Monday, June 22, 2026, in the journal Nature, estimated that the comet formed about 10 to 12 billion years ago. As our solar system is around 4.5 billion years old, this makes 3I/ATLAS likely the oldest known object ever to pass through it.

An interstellar object is a body, such as a comet or asteroid, that comes from outside our solar system. It forms around another star and later travels through space into our region. 3I/ATLAS is only the third such interstellar object ever observed. The first two were named 1I/’Oumuamua, found in 2017, and 2I/Borisov, found in 2019.

Researchers used the James Webb Space Telescope to study the chemical make-up of the comet, which is about 2.6 km wide. They measured the ratios of isotopes, which are different versions of elements such as hydrogen and carbon. These ratios gave clues about the temperature and conditions in the distant planetary system where the comet was born, which appears to have been much colder and less rich in metals than our own.

Importantly, the comet was found to be rich in organic molecules containing carbon, hydrogen, nitrogen, oxygen and sulphur. Scientists said this shows that the building blocks linked to life were present even in such a cold and distant region. 3I/ATLAS is now approaching the orbit of Saturn and is expected to leave the outer edge of the solar system around 2035.

For exam preparation, this discovery is useful for understanding interstellar objects, comets, the role of the James Webb Space Telescope, and how isotopes help scientists study the origins of space bodies.