- 3I/ATLAS is the third confirmed interstellar object passing through our Solar System
- It was discovered on July 1, 2025, moving at 137,000 mph near Jupiter's orbit
- 3I/ATLAS follows a hyperbolic trajectory, indicating it is not bound to the Sun
3I/ATLAS, the third known interstellar object to enter our solar system, after 'Oumuamua (discovered in 2017), was the first such object, and the second was 2I/Borisov (discovered in 2019). It is set to make its closest approach to Earth on December 19, 2025. The space object has created a buzz worldwide with many scientists questioning its origin and pointing to its various anomalies. Avi Loeb, who is a prominent Harvard scientist, has often discussed that 3I/ATLAS might not be naturally occurring and could be an "alien" technology. But when NASA released images of 3I/ATLAS, it referred to it as a "comet", debunking various theories.
Also read | Ahead Of Closest Approach To Earth, A Look At 3 Latest Images Of Interstellar Comet 3I/ATLAS
Here are NASA-approved answers to some frequently asked questions about Comet 3I/ATLAS:
1. What is 3I/ATLAS?
3I/ATLAS is the third confirmed interstellar object (ISO) to pass through our Solar System, discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) station in Chile. It's named 3I/ATLAS because it is the third (3) interstellar (I) object found passing through our solar system, and it was discovered by the ATLAS survey telescope. According to NASA, the comet was moving at about 137,000 miles per hour (221,000 kilometres per hour) when it was discovered. At perihelion, which is the closest approach to the Sun, its speed increased to about 153,000 miles per hour (246,000 kilometres per hour) as it was pulled by the Sun's gravity.
Also read | Advanced Civilisations Could "Seed" Life On Earth By Interstellar Objects, Scientist Claims
2. Where did 3I/ATLAS come from?
3I/ATLAS originated from interstellar space, likely from the Milky Way's thick disk, making it possibly the oldest comet ever seen, with an estimated age of 7.6-14 billion years. NASA mentioned that the comet has been approaching from the general direction of the constellation Sagittarius, where the central region of our galaxy is located. At the time of its discovery, 3I/ATLAS was about 410 million miles (670 million kilometres) away from the Sun, within the orbit of Jupiter.
Also read | Interstellar Comet 3I/ATLAS Turns Green Ahead Of Closest Approach To Earth
3. What is unique about 3I/ATLAS?
3I/ATLAS is an active comet with a hyperbolic trajectory, displaying clear cometary activity, and has the highest orbital eccentricity (6.139) of any known interstellar object.
4. Why are scientists sure that the comet didn't originate in our solar system?
As mentioned, it is on what is known as a hyperbolic trajectory and moving too fast to be bound by the Sun's gravity. 3I/ATLAS does not follow a closed orbital path around the Sun and is just passing through our solar system and will continue its journey into interstellar space, never to be seen again. When it leaves our solar system, it will be at the same speed as it came in.
Also read | 3I/ATLAS Still Shows Anti-Tail Ahead Of Closest Approach To Earth, Says Harvard Scientist
5. Is 3I/ATLAS a threat to Earth?
No, 3I/ATLAS poses no threat to Earth. As per NASA, 3I/ATLAS will come no closer than 170 million miles (270 million kilometres), or 1.8 astronomical units.
6. How big is 3I/ATLAS, and what is it made of?
Scientists are not sure about its size yet, but as per Hubble Space Telescope observations as of August 20, 2025, the diameter of its nucleus is not less than 1,400 feet (440 meters) and not greater than 3.5 miles (5.6 kilometres). 3I/ATLAS is rich in carbon dioxide, water ice and other gases, with a reddish colour similar to D-type asteroids and 2I/Borisov.
7. Can I see 3I/ATLAS with the naked eye?
No, 3I/ATLAS is not visible to the naked eye, requiring telescopes for observation.
8. What is the significance of 3I/ATLAS?
3I/ATLAS offers a rare opportunity to study material from another star system, providing insights into the formation and composition of objects in distant star systems.
9. Has 3I/ATLAS been observed in X-rays?
Yes, ESA's XMM-Newton space observatory captured 3I/ATLAS in X-ray light, revealing a massive debris cloud and natural comet behaviour.
10. What can we learn from 3I/ATLAS?
Studying 3I/ATLAS can help scientists understand the nature and history of interstellar objects, their composition, and potential implications for our understanding of the universe.
