Mysterious Interstellar Comet 3I/ATLAS May Be Nuclear-Powered and Emitting Its Own Light, Harvard Expert Says

Astronomers have confirmed that the newly discovered interstellar comet 3I/ATLAS is racing toward the inner Solar System, and early data suggest it could be the most intriguing visitor since 1I/ʻOumuamua and 2I/Borisov. Detected on 1 July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) station in Chile, 3I/ATLAS was already 4.5 AU from the Sun and moving at nearly 68 km s⁻¹—fast enough to escape the Sun’s gravity once its fly-by is complete. What makes 3I/ATLAS special? • Third confirmed interstellar object (prefix “I”) and first whose icy coma was visible almost immediately, marking it as an active comet rather than a dry asteroid. • Highly eccentric, retrograde orbit (e≈6.14; inclination≈175°) indicates a deep-space origin far outside the Oort Cloud. • Perihelion will occur around 30 October 2025 at 1.4 AU—just inside Mars’s orbit—giving professional and advanced amateur telescopes a multi-week observing window. • Initial photometry hints that the nucleus may span 0.3–5 km, but volatile jets already produce a coma larger than Earth. Brightness anomaly fuels debate Within weeks of discovery, a Harvard-Smithsonian group reported that 3I/ATLAS appears — at certain wavelengths — to emit more light than can be explained by solar reflection alone, raising speculative ideas ranging from crystalline ice fluorescence to exotic energy sources. Most comet researchers attribute the excess glow to unusually efficient dust-grain scattering, but follow-up spectra scheduled on JWST and ESO’s VLT should settle the question before perihelion. Timeline and sky-watching guide • Now–Sept 2025: magnitude 15–16, accessible only to large research telescopes; orbit refinements expected weekly. • Early Oct 2025: predicted to brighten to magnitude 12, entering reach of 30 cm amateur instruments under dark skies. • 30 Oct 2025 (perihelion): peak brightness near magnitude 10; best chance for DSLR astrophotography in Taurus before dawn. • Nov 2025–Jan 2026: fades and exits Solar System toward the constellation Auriga, never to return. Comparisons with ‘Oumuamua and Borisov Unlike 1I/ʻOumuamua, which was inactive and oddly elongated, 3I/ATLAS behaves like a “textbook comet,” giving scientists precise coma spectra and direct gas measurements for the first time on an interstellar body. Its activity also differs from 2I/Borisov, which remained compact; ATLAS is already shedding dust fans hundreds of thousands of kilometers wide, offering a laboratory for studying primordial ices from another star system. Potential spacecraft interception Preliminary trajectories show that a rapid-launch CubeSat mission from Mars orbit—or a solar-sail deployed from Earth as early as December—could overtake 3I/ATLAS by mid-2026. NASA’s Planetary Defense team is reviewing feasibility studies, seeing the comet as a unique target for collecting unprocessed extrasolar material without waiting decades for future arrivals. Why this matters for planetary science 1. Chemical fingerprints of 3I/ATLAS may reveal which volatiles survived planetary migration in other stellar nurseries. 2. Dust-to-gas ratios will test models of comet formation beyond the snow line in protoplanetary disks. 3. Measuring isotopes such as ³H/¹H and ¹⁵N/¹⁴N could illuminate how water and organics are distributed in the Milky Way. Public-engagement tips • Follow #3IATLAS on social media for real-time images from professional observatories. • Planetarium apps will update ephemerides daily; input orbital elements to overlay the path. • Local astronomy clubs plan livestreams during perihelion week—check regional observatory schedules. FAQ Will 3I/ATLAS be visible to the naked eye? No; current models cap peak brightness at magnitude 10, requiring at least binoculars under dark skies. Is there any impact threat? None. The comet never approaches closer than 130 million km and is on a hyperbolic escape path. Could it be alien technology? Unlikely. While brightness puzzles persist, natural explanations dominate peer-reviewed discussions. Bottom line 3I/ATLAS offers a once-in-a-generation opportunity to study fresh material from another star system without leaving our own. As its dusty halo brightens this autumn, sky-watchers, citizen scientists, and planetary-defense planners alike will keep their eyes—and instruments—trained on this swift interstellar messenger.