Science & technology

Interstellar Comet Discovered Racing Through Solar System

JUL 3 2025·Updated JUL 5 2025

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Above: Interstellar comet 3I/ATLAS as on July 3, 2025. Image credit: NASA/JPL-Caltech/Wikimedia Commons

The Facts

NASA's Asteroid Terrestrial-impact Last Alert System detected 3I/ATLAS on Tuesday, the third interstellar object ever detected in the solar system, classified as a comet due to its fuzzy appearance and short tail.
Google
NASA Science
The interstellar comet, potentially the largest ever detected, is 10-20 kilometers (6.2-12.4 miles) wide and traveling at speeds exceeding 60 kilometers per second, indicating it's not bound to the Sun.
CBC
Google
3I/ATLAS will reach its closest approach to the Sun on Oct. 29-30, 2025, coming within 1.4 astronomical units, or approximately 130 million miles of our star, just inside Mars' orbit. The comet poses no threat to Earth, maintaining a minimum distance of 1.6 astronomical units or about 150 million miles from our planet throughout its journey.
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NASA Science
The comet's trajectory indicates it originated from interstellar space, arriving from the direction of the constellation Sagittarius, and will exit the solar system after its solar flyby. Professional and amateur astronomers worldwide have traced the object's path back to June 14 using archived telescope data from multiple observatories.
Live Science
BBC Sky at Night Magazine
France 24
Scientists estimate up to 10,000 interstellar objects may drift through the solar system at any given time, though most would be smaller than 3I/ATLAS. The newly operational Vera C. Rubin Observatory in Chile could potentially discover these dim interstellar visitors on a monthly basis, significantly increasing detection rates.
The Straits Times
New Scientist
This discovery follows two previous interstellar objects: 'Oumuamua in 2017, known for its unusual traits, and comet 2I/Borisov in 2019. Teams worldwide are racing to study 3I/ATLAS's composition, shape, and rotation before it gets too close to the Sun.
CBC
Google

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The Spin

Narrative A

This remarkable discovery showcases humanity's advancing astronomical capabilities and our growing understanding of interstellar visitors. The detection of 3I/ATLAS proves these cosmic wanderers regularly traverse our solar system, offering unprecedented opportunities to study materials from other star systems. Advanced survey systems like ATLAS demonstrate how modern technology protects Earth while expanding scientific knowledge.

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NASA Science

Narrative B

While fascinating from a scientific perspective, the discovery raises questions about how many similar objects pass undetected through our solar system. The object's massive size and high velocity highlight the unpredictable nature of interstellar visitors and the challenges they pose for comprehensive space monitoring. Current technology limitations prevent intercepting such objects for detailed study, restricting research to distant observations.