Traveling at speeds above 30 kilometers per second along a hyperbolic trajectory, the comet 3I/Atlas is the third confirmed interstellar object to enter the Solar System. The Atlas survey system in Chile first identified the body on July 1, 2025. Because the object originated outside the local stellar neighborhood, its passage offers researchers direct access to materials formed in distant cosmic environments.

Research teams are using instruments such as the James Webb Space Telescope to examine the chemical makeup of the visitor. The object poses no collision threat to Earth, maintaining a minimum approach distance of 270 million kilometers from the planet. Tracking campaigns cover its perihelion, the point of closest approach to the Sun, at a distance of 210 million kilometers.

Spectroscopic readings from the observation campaign show that the detected materials include a high concentration of carbon dioxide ice. These measurements allow astronomers to compare the raw ingredients of foreign star systems with those found in the local neighborhood.

Alongside the frozen carbon dioxide, the presence of water vapor and carbon monoxide sets 3I/Atlas apart from comets native to the Solar System. The ratio of these volatile gases provides a chemical fingerprint of the region where the body first coalesced.

Orbital calculations indicate that gravitational forces ejected the comet from another star system billions of years ago. Since that expulsion, the object has traveled through interstellar space before crossing into the gravitational reach of the Sun.

Routine sky surveys in the Atacama Desert identified the unbound orbit

The Atlas network first recorded the comet during routine sky monitoring operations in the Atacama Desert in Chile. Preliminary astrometric data immediately indicated that the object followed an open orbit not gravitationally bound to the Sun.

Subsequent trajectory calculations verified that its velocity exceeds the escape speed of the Solar System. Within a few days of the initial sighting, international astronomy teams confirmed its classification as an interstellar object.

Frozen carbon dioxide dominates the one-kilometer core

Spectroscopic analysis revealed a predominance of frozen carbon dioxide across the surface of the comet. This specific chemical trait indicates that the body formed at temperatures below -100°C within the outer regions of another planetary system.

Water vapor appears in smaller quantities than astronomers typically observe in native solar comets. Carbon monoxide rounds out the volatile profile recorded by spectrographs during the approach.

Estimates derived from brightness measurements place the diameter of the solid nucleus at approximately 1 kilometer. Cometary activity rises as the object moves closer to the Sun, releasing trapped gases that form a visible coma around the core.

Read also: Interstellar comet 3I/ATLAS yields new flight path calculations for deep space origin

More than 50 institutions in 20 countries coordinate infrared and optical tracking

Ground-based observatories located in Hawaii and Spain track daily changes in the structure and brightness of the comet. At the same time, the James Webb Space Telescope captures infrared imagery to map how materials are distributed across the coma.

The observational data feeds into computer models that simulate chemical evolution inside protoplanetary disks. This international monitoring effort involves more than 50 scientific institutions across 20 countries.

Solar gravity exit speed exceeds 40 kilometers per second after Mars orbit crossing

Following its closest approach to the Sun, the comet accelerates on its outbound path away from the Solar System. Its final velocity exceeds 40 kilometers per second as it leaves the gravitational influence of the Sun.

The outbound trajectory took the object across the orbit of Mars in December 2025. Ground-based optical observations concluded in mid-2026 due to the increasing distance and fading light of the departing body.

Gas tail and fine dust absence distinguish 3I/Atlas from 1I/Oumuamua and 2I/Borisov

Unlike 1I/Oumuamua, the first known interstellar visitor, which showed no cometary activity, 3I/Atlas displays an active gas tail. When compared to the second confirmed visitor, 2I/Borisov, the comet holds a higher relative proportion of carbon dioxide.

These physical and chemical differences point to a wide variety of formation processes across interstellar space. Each detected object supplies distinct data regarding the environmental conditions inside distant stellar nurseries.

Sublimation rates rise by 20 percent per million kilometers toward the Sun

High-resolution instruments aboard the participating telescopes detect specific molecular emissions coming from the nucleus. The resulting spectra confirm the absence of the fine dust particles typically found in comets that originate within the Solar System.

The rate of ice sublimation increases by 20 percent for every million kilometers the comet travels closer to the Sun. Observation models set the peak brightness of the object at magnitude 10 during its active phase.