The interstellar comet 3I/ATLAS has been recognized as one of the oldest comets ever observed by astronomers. New data obtained with the James Webb Space Telescope (JWST) suggest that this object could be as much as 12 billion years old. Analysis of the comet’s isotopic composition indicates it originated in the cold, distant regions of the early Milky Way.

Discovery and Observations

Comet 3I/ATLAS was discovered last year as it traveled through the Solar System. Various theories about its nature were previously proposed, but recent observations with JWST have confirmed its natural, interstellar origin.

Age and Origin

Research shows that 3I/ATLAS formed in a remote and cold part of the Milky Way galaxy. Its estimated age ranges from 10 to 12 billion years, which is more than twice the age of Earth and the Solar System. The comet’s age is close to that of the Milky Way itself (13.6 billion years) and the Universe (13.8 billion years).

JWST Telescope Data

During the comet’s flyby in late 2025, JWST collected new information about the gases released as the Sun heated the comet’s surface and the ice began to evaporate. These findings helped refine estimates of the object’s age and origin.

Isotopic Analysis

Earlier, the age of 3I/ATLAS was estimated to be between 3 and 11 billion years. However, its isotopic composition is significantly different from that of comets in the Solar System, indicating it formed 10–12 billion years ago.

Physical Characteristics and Trajectory

The comet measures about 440 meters long and 5.6 kilometers wide. According to data from the Hubble Space Telescope, 3I/ATLAS entered the Solar System at a speed of around 221,000 km/h. The closest approach to Earth was 270 million kilometers, recorded on December 19, 2025.