Interstellar visitor
3I/ATLAS
3I/ATLAS is the third known visitor from another star. It came in 2025 and may even be older than our Sun!
Fact file
- Type
- Interstellar visitor
- Diameter of the nucleus
- 5 km
- Orbit
- open (hyperbola) – will never return
- Closest point to the Sun
- passed on 29 October 2025
Interesting facts about 3I/ATLAS
- The third known interstellar visitor, discovered on 1 July 2025 by the ATLAS telescope network in Chile.
- It is the fastest of the three: it came in from space at about 58 km/s – the Sun could hardly bend its path.
- It could be older than our Solar System – possibly more than 7 billion years old.
Origin
It comes from the direction of the constellation Sagittarius, that is, from towards the centre of the Milky Way, and probably stems from a very old generation of stars.
Coma and tail
On its way towards the Sun it developed a coma and a tail.
Exploration
Several space probes observed it from near Mars as it flew past there in October 2025.
Connection with Earth
Its path is almost a straight line – and it flies almost exactly in the plane of the planets, but in the opposite direction.
This site is free and has no banner ads. Here is how you can support it