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Comet 3I/ATLAS

Cataloguing the journey of comet 3I/ATLAS through the solar system. Because the object comes from outside our solar system, it is just passing through – so we use all the tools at our disposal to observe it before it disappears back into the cosmic dark. A host of NASA missions are coming together to observe this interstellar object, which was first discovered in summer 2025, before it leaves forever. While the comet poses no threat to Earth, NASA’s space telescopes help support the agency's ongoing mission to find, track, and better understand solar system objects.

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NASA/ESA’s SOHO Observes Interstellar Comet 3I/ATLAS

The ESA (European Space Agency) and NASA Solar and Heliospheric Observatory, or SOHO, spacecraft captured a glimpse of interstellar comet 3I/ATLAS on Oct. 15–26. During this time period, the spacecraft’s Large Angle and Spectrometric Coronagraph (LASCO) instrument suite spotted the comet crossing its field of view from approximately 222 million miles (358 million kilometers) away, or more than twice Earth’s distance from the Sun.

A faint, slightly yellowish point of light—Comet 3I/ATLAS—appears near the center of a grainy, brown-toned background captured by the SOHO/LASCO C3 coronagraph between October 15–26, 2025. The comet is only marginally brighter than the surrounding noise, making it difficult to distinguish.
A faint image of comet 3I/ATLAS as observed by ESA/NASA’s SOHO mission between Oct. 15-26, 2025. The comet appears as a slight brightening in the center of the image.
Lowell Observatory/Qicheng Zhang

The SOHO spacecraft orbits the Sun-Earth Lagrange point 1, a region of gravitational balance approximately one million miles closer to the Sun along the Sun-Earth line. Comet 3I/ATLAS was expected to be too faint for SOHO to see, but detailed image processing and overlaying (or “stacking”) subsequent telescope images ultimately generated the image shown above, where the comet appears as a slight brightening in the center. Several other NASA spacecraft are imaging the historic interstellar visitor as it passes through the solar system.

Launched in 1995, the SOHO spacecraft has become the most prolific comet hunter of all time. With the help of citizen scientists participating in the NASA-funded Sungrazer Project, SOHO’s imagery has led to the discovery of more than half of all known comets (over 5,186 as of this writing).

By Miles Hatfield
NASA’s Goddard Space Flight Center, Greenbelt, Md.