'Oumuamua's 2018 Acceleration Still Defies Explanation as 2 Later Interstellar Objects Look Like Ordinary Comets
Updated
Updated · spacedaily.com · Jun 1
'Oumuamua's 2018 Acceleration Still Defies Explanation as 2 Later Interstellar Objects Look Like Ordinary Comets
3 articles · Updated · spacedaily.com · Jun 1
A tiny extra push away from the Sun, reported in 2018, remains the central mystery around 1I/'Oumuamua because its trajectory could not be explained by gravity alone.
Roughly 2 weeks of observations after its 19 October 2017 discovery showed no coma, tail or dust, leaving scientists with comet-like acceleration but no visible outgassing to drive it.
Natural explanations still dominate: models including nitrogen ice and a 2023 hydrogen-release mechanism try to explain an invisible thrust, while Avi Loeb's artificial-origin idea remains outside the mainstream.
The debate stays open because 'Oumuamua was a few hundred metres across, seen briefly after perihelion, and is now unreachable, so every theory is fitted to one sparse dataset.
Two later interstellar visitors—2I/Borisov in 2019 and 3I/ATLAS in 2025—showed ordinary cometary activity, and the Vera C. Rubin Observatory is expected to find more objects that could finally put 'Oumuamua in context.
A new super-telescope is hunting interstellar objects. Will we find more alien relics or prove 'Oumuamua was unique?
With new interstellar comets looking normal, what really pushed the silent visitor 'Oumuamua through our solar system?
An interstellar comet carries 12-billion-year-old water. What secrets of the galaxy's birth does this ancient visitor hold?
The First Three Interstellar Visitors: Scientific Breakthroughs, Controversies, and the Future of ISO Exploration
Overview
The study of interstellar objects (ISOs) is advancing quickly, moving from rare discoveries to more routine observations. A key example is the interstellar comet 3I/ATLAS, which made a close approach to Earth in December 2025 and was tracked by NASA as it passed Jupiter in 2026. This progress is possible thanks to collaborative efforts and advanced technology, like the Vera C. Rubin Observatory’s powerful camera, which captured detailed images of 3I/ATLAS. These developments show how new tools and teamwork are helping scientists better understand material from beyond our solar system, marking the start of a new era in space exploration.