3i/atlas: What today’s ‘Manhattan-size’ interstellar visitor really means

Interstellar visitor passes Sun safely

3I/ATLAS is making its closest swing by the Sun at roughly 130 million miles (well inside Mars’ orbit), passing about 170 million miles from Earth—no threat, and not visible from Earth because it’s lost in solar glare. While backyard observers will miss it, a handful of spacecraft are positioned to gather data as it flies back out of the solar system, according to a report in the New York Post.

What 3I/ATLAS is

3I/ATLAS is an interstellar object — the third known visitor from beyond our solar system — now sweeping past the Sun on a one-off, hyperbolic path. It isn’t bound to the Sun like a regular comet. Think of it as a fast flyby from deep space rather than a new solar-system resident.

How close it gets (and whether that’s risky)

At perihelion, 3I/ATLAS comes to roughly 130 million miles from the Sun, just inside Mars’ orbit. Its closest pass to Earth is about 170 million miles. Those distances are huge on human scales and pose no impact threat. Trajectory models show it will slingshot back into interstellar space after the encounter.

Can you see it from Earth?

Not during perihelion. The object is buried in solar glare from our vantage point. Ground telescopes and most Earth-orbiting instruments will miss the moment. It should re-emerge from the Sun’s vicinity later, but for now it’s effectively invisible to backyard observers and most big observatories alike.

Who will observe it anyway

Spacecraft positioned around the inner solar system can still take a look. Orbiters at Mars, NASA’s Psyche mission en route to the main belt, and the Lucy mission to Jupiter’s Trojan asteroids are among the likely watchers. ESA’s JUICE spacecraft may have the best geometry to study it, but because its high-gain antenna is currently protecting instruments from the Sun, data relay to Earth is expected to lag by months.

The ‘alien engine’ debate

Harvard astronomer Avi Loeb has argued that 3I/ATLAS shows unusual behaviour — reports of non-gravitational acceleration, a colour shift, and an anti-tail aligned sunward — and has speculated that it could be artificial. He has also questioned the availability of certain images rumoured from Mars-orbiting cameras. NASA’s public stance is straightforward: 3I/ATLAS presents no hazard, and there’s no confirmed evidence it is anything other than a natural interstellar object. As with earlier interstellar visitors, extraordinary claims will rise or fall on data that can be independently checked.

Why scientists are excited anyway

Natural or not, 3I/ATLAS is scientifically valuable. Interstellar objects carry chemistry and structure forged around other stars. Measuring its brightness changes, colour, dust behaviour, and any outgassing helps researchers compare it with objects like ‘Oumuamua and 2I/Borisov, refine how interstellar bodies form, and sharpen models that assess potential hazards from truly threatening visitors. Even a handful of well-timed spacecraft observations can tell us about its composition, rotation, and surface physics.

What happens next

As it rounds the Sun and heads out, 3I/ATLAS will fade and geometry will improve for some instruments. Expect trickles of data from deep-space missions first, then lab analyses and papers piecing together its behaviour near perihelion. If additional images or spectra surface from planetary orbiters, they’ll help settle questions about dust tails, colour changes, and any subtle accelerations.

Bottom line

3I/ATLAS is a rare, distant flyby — closer than Mars but still millions of miles from Earth. You won’t see it from your balcony, but a network of spacecraft should capture useful snapshots. The sensational theories will get headlines; the careful measurements will shape what we actually learn.