NASA's Hubble Tracks Alien Comet Moving At 36-Miles/Sec Towards Sun

Forbes

3 days ago

Astronomers using NASA's Hubble Space Telescope have captured the sharpest-ever image of comet 3I/ATLAS — an 'interstellar interloper' — revealing it to be the fastest ever comet seen so far.
The comet, first spotted by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) on July 1, 2025, comes from another star system. It's only the third confirmed interstellar object ever detected.
36 Miles Per Second
3I/ATLAS is traveling through our solar system at a staggering 130,000 miles (209,000 kilometers) per hour — or 36 miles per second (58 kilometers per second) — the highest velocity ever recorded for a solar system visitor. It appears to be behaving like a normal solar system comet, with Hubble capturing a dust plume ejected from the sun-facing side of the comet alongside a dust tail streaming away from the nucleus.
Astronomers believe this record-breaking speed is the result of countless gravitational encounters during its interstellar voyage. "It's like glimpsing a rifle bullet for a thousandth of a second. You can't project that back with any accuracy to figure out where it started on its path,' said David Jewitt of the University of California, Los Angeles, science team leader for the Hubble observations, in a press release.
Largest Ever Interstellar Object
Far larger than either of the other two interstellar comets found in recent years — 1I/'Oumuamua in 2017 and 2I/Borisov in 2019 — the arrival of 3I/ATLAS offers scientists a rare opportunity to study a visitor from another star system. However, it's proving difficult to observe. Hubble's new observations suggest the comet's icy nucleus could be as large as 3.5 miles (5.6 kilometers) in diameter, but it may also be as small as 1,000 feet (320 meters), say the authors of a new paper published on arXiv, a platform for disseminating research, but which isn't yet peer-reviewed. It's due to be published in The Astrophysical Journal Letters. Other large telescopes have had a similar problem, including the James Webb Space Telescope, TESS (Transiting Exoplanet Survey Satellite), the Neil Gehrels Swift Observatory and the W.M. Keck Observatory.
Where Did 3I/ATLAS Come From?
The speed at which 3I/ATLAS is traveling makes observations very difficult. 'No one knows where the comet came from,' said Jewitt. 'This latest interstellar tourist is one of a previously undetected population of objects bursting onto the scene that will gradually emerge."
The detection of 3I/ATLAS has been possible because of powerful sky survey capabilities, something that's about to be bolstered even further with the opening of the Vera C. Rubin Observatory. It has already detected interstellar object 3I/ATLAS and may detect up to 50 more during its 10-year mission, according to a new model. "We've crossed a threshold," said Jewitt.
Threat To Earth
3I/ATLAS poses no threat to Earth — in fact, it's passing through the opposite side of the sun to where Earth currently is and will make its closest approach to the sun in October, when it will be behind the sun and be lost in its glare from Earth's point of view. It will pass relatively close to Mars.
3I/ATLAS should remain visible to ground-based telescopes until September, when it will pass too close to the sun to observe, but it's expected to reappear by early December as it departs the inner solar system.
Wishing you clear skies and wide eyes.