Interstellar comet 3I/ATLAS detected by NOAA satellite despite being hidden by intense sunlight
The comet 3I/ATLAS, the third identified interstellar object in the Solar System, was captured in images even while positioned behind the Sun between October and November 2025. Amateur astronomer Worachate Boonplod used data from the CCOR-1 coronagraph, installed on the NOAA’s GOES-19 satellite, to record the visitor. The detection occurred amid the perihelion scheduled for October 29, when the comet reaches its closest point to the star.
Observation becomes feasible thanks to the instrument that blocks intense light from the solar disk. Ground-based telescopes cannot access the comet during this period due to excessive brightness. The 3I/ATLAS was discovered on July 1, 2025, and follows a hyperbolic trajectory.
- Origin: another region of the Milky Way.
- Predecessors: 1I/‘Oumuamua (2017) and 2I/Borisov (2019).
- Recent feature: development of an antitail.
Trajectory and observation challenges
The comet approaches perihelion at a distance that intensifies solar radiation. This proximity causes heating and possible release of dust and gases.
Scientists monitor brightness and activity to analyze composition. Fragmentation may occur, similar to what was observed in 2I/Borisov.
CCOR-1 instrument in operation
The CCOR-1 coronagraph studies the solar corona and events such as coronal mass ejections. It records objects near the Sun by filtering disk light.
Daily images show 3I/ATLAS as a bright point with diffuse coma. No tail is visible in the captures processed by Boonplod.
History of interstellar objects
The 1I/‘Oumuamua raised hypotheses of extraterrestrial technology in 2017. NASA studies confirmed the asteroid’s natural nature.
The 2I/Borisov exhibited typical cometary behavior in 2019. Both follow hyperbolic orbits, indicating a single passage through the Solar System.
The 3I/ATLAS generates valuable data on materials from other stars. Monitoring continues until March 2026, when the comet will leave the system.
Details of the amateur detection
Worachate Boonplod analyzed sequences from GOES-19 in Earth orbit. Processing highlighted the comet in a specific square in the images.
The coma appears with slight diffusion around the nucleus. Absence of tail reflects the observation angle.
Ongoing scientific monitoring
CCOR-1 data allow real-time tracking of perihelion. Solar heating reveals the comet’s chemical elements.
Comparisons with Borisov help understand variations in interstellar visitors. Information contributes to stellar formation models.
Future visibility prospects
The comet will emerge from solar glare in November 2025. Ground-based telescopes will resume direct observations.
Hyperbolic trajectory leads to definitive exit in March 2026. Satellites like ESA’s ExoMars TGO have already captured sequences from Mars.
Composition and behavior
The 3I/ATLAS displays a recently confirmed antitail. The phenomenon occurs due to interaction with solar wind.
Gas release indicates presence of volatiles. Spectral analysis will identify unique components.
NOAA contributions
The GOES-19 satellite operates in geostationary position. CCOR-1 provides daily images for space weather.
Detection validates the instrument’s capability for sungrazer comets. Data are public via specialized platforms.
Monitoring continues with focus on nucleus integrity. Fragmentation would provide indirect samples of interstellar material.
