3I/ATLAS Update: Harvard Expert Avi Loeb Warns Interstellar Objects Still Need to be Figured Out

Imagine flying through space at speeds that defy the rules of our solar system, only for scientists to observe behaviour that challenges everything we thought we knew about cosmic wanderers. Astronomers are baffled by new information about the interstellar comet 3I/ATLAS, which cannot be explained by gravity and sunlight alone.

This comes as asteroid 99942 Apophis is set to approach Earth in 2029. The NASA-funded ATLAS survey in Chile first spotted 3I/ATLAS on July 1, 2025. It is only the third confirmed interstellar visitor to our solar system, following 'Oumuamua and 2I/Borisov.

Astronomers can track the object's motion and brightness changes using optical, infrared and ultraviolet instruments. Its movements and fluctuating brightness do not fit with what is known about small bodies moving through our cosmic neighbourhood.

On Dec. 19, 2025, 3I/ATLAS made its closest approach to Earth, passing about 270 million kilometres away — nearly twice the distance from the sun. It was travelling at an astonishing speed of 58 kilometres per second. These findings raise the stakes for planetary defence efforts worldwide, as Apophis is expected to pass within 32,000 kilometres of Earth on April 13, 2029, closer than some satellites.

3I/ATLAS Upends Asteroid Tracking Norms

The 3I/ATLAS study, drawing from frame-by-frame image comparisons across multiple platforms, reveals small but measurable changes in velocity and direction over time. Brightness variations cropped up too, often tying to directional shifts rather than mere distance from the sun, while some images captured material structures forming and fading without clear symmetry. These oddities, confirmed by independent observers, suggest even tiny, consistent forces could nudge an object's path over long hauls – a wrinkle that demands closer scrutiny as we brace for Apophis.​​

Harvard astrophysicist Avi Loeb puts it bluntly: interstellar objects 'are a new class of objects that still need to be figured out'. Loeb has highlighted several 'anomalies,' including the object's rare 'anti-tail' stretching toward the sun and its unusual chemistry — specifically a plume of nickel with very little iron, which he suggests mirrors industrial-rich alloys used in aerospace applications.

Unlike purely theoretical work, this analysis leans on hard observational data, marking a leap in probing these rare visitors from beyond our solar system. For everyday stargazers and policymakers alike, it underscores a sobering truth: our defences hinge on nailing unpredictable behaviour, lest a future rock slips through the cracks.​

Apophis itself poses no collision risk in 2029, per NASA's Planetary Defense Coordination Office: 'Apophis poses no impact threat in 2029 based on current observations'. Yet its flyby offers a golden chance to gather radar data, thermal readings, and structural intel, especially as Earth's gravity might tweak its spin. Agencies like NASA, the European Space Agency, and Japan's Aerospace Exploration Agency are ramping up tracking from late 2028 into April 2029 – the crunch window for the best data haul.​​

3I/ATLAS Fuels Apophis Flyby Preparations

What makes 3I/ATLAS so intriguing is how its anomalies challenge assumptions baked into planetary defence planning. Loeb has famously criticized the 'bureaucratic' delay in releasing high-resolution imagery from NASA's Mars Reconnaissance Orbiter, arguing that prioritizing science over gatekeeping is essential to identifying if such objects are natural rocks or potentially 'technological' in origin.

Analysts found that changes in motion weren't fully explained by gravity or solar heating. This suggests that there are internal structures or external reactions that we still don't fully understand. This isn't an abstract puzzle. With the population of Earth growing and cities spreading out, perfect tracking keeps disasters from happening. Think of tsunamis caused by an unseen impactor or worse.​

The report says that getting ready is more important than guessing: check models against real data, test response systems, and improve simulations with new information. Small forces at work, as shown here, could grow into big ones, changing paths in ways that need close watching. As Apophis gets closer, expect close-up views to show its secrets, just like 3I/ATLAS has made us rethink the small things that could hurt us.​

The stakes for humanity are very high. Billions of people depend on these space sentinels to keep doomsday rocks away, turning strange data into life-saving watchfulness. Even though 2029 doesn't bring about the end of the world, it does show how much we still don't know about the universe.

For example, interstellar oddballs like 3I/ATLAS remind us that the universe still has some surprises up its sleeve. The comet is now racing towards Jupiter and will leave our solar system for good by March 2026. The question is whether we are really ready for the next visitor from space.