Since it was discovered by a telescope in Chile In July 2025, the comet 3I/ATLASthird interstellar object confirmed to visit our solar system, it became a mysterious magnet for science. Astronomers of Oxford they indicated that It has been wandering the Milky Way for almost 3 billion years.
Last November he made its closest pass to Earth before heading beyond the solar system. When the comet began to move away from the Solastronomers took the opportunity to study its chemical composition. It is believed that it may have formed in an ancient, frigid planetary system with an extremely cold environment.
According to the astronomer Oxford University, Matthew Hopkinswho presented conclusions at the Royal Astronomical Society (Royal Astronomical Society in English), a leading British scientific organization based in London, said it could be more than 7 billion years old.
7 billion years old and 3 billion years traveling: what is the interstellar comet 3I/ATLAS
Until now, non-interstellar comets such as Halley’s cometwere formed together with our solar system, so they are up to 4.5 billion years old, which would leave this as the oldest.
It was discovered by the ATLAS survey telescope in Río Hurtado, Chile. Among others, also the famous space telescope James Webb and the observatory ALMA (Atacama Large Millimeter/submillimeter Array)also Chilean, studied 3I/ATLAS. Although it still has many mysteries, the object was closely observed and several certainties have been discovered.
The international environment Space Dailya specialist in Space issues, made a compilation of studies on the matter and synthesized that it was formed in a part of the galaxy called the «thick disk», where the stars are older than almost everything else that humanity observed.
It is the third interstellar object (to visit us from beyond our Solar System), after 1I/’Oumuamua in 2017 and 2I/Borisov in 2019. It was named 3I/ATLAS in honor of its discovery.
The Royal Astronomical Society said of Hopkins’ analysis that the object has about a two-thirds chance of being older than the solar system, with an optimal statistical estimate of approximately 7 billion years. This makes the comet the oldest thing humanity has ever observed.
Regarding the so-called «thick disk», it is indicated that since the Milky Way is not a uniform structure, most of its stars –including the sun-, are found in a relatively thin disk that rotates around the galactic center. This is a flat layer of young stars.
Beneath this disk, there is a thicker, larger and more diffuse structure called the thick disk, with a population of older stars, which orbit the galaxy in inclined paths and they pass through the thin disk rather than residing within it. 3I/ATLAS would have arrived from an angle that refers directly to the population of the thick disk.
However, it is clarified that the thick disk is older than the thin disk, but it is not the oldest component of the galaxy. The stellar halo of the Milky Way contains stars approximately 12 to 13 billion years old. In addition, it was detailed that the two previous interstellar objects originated from the thin disk.
