Archive · 19 Dec 2025
Interstellar Comet 3I/ATLAS Approaches Earth
A comet named 3I/ATLAS is visiting our solar system.
It will be closest to Earth on 19 December 2025, about 170 million miles away.
You can see it with binoculars or a telescope in the early morning sky.
Scientists say it's a comet, not an alien spaceship, even though some people thought it might be.
It's only the third interstellar comet we've ever seen.
The other two were named 'Oumuamua and Borisov.
NASA has shared pictures and observations to prove it's just a comet.
The comet is traveling very fast and has a bright green hue, which scientists believe is due to chemical reactions with the Sun.
Interstellar comet 3I/ATLAS will be closest to Earth on 19 December 2025 at 170 million miles.
Visible through binoculars or telescopes with at least a 30-centimeter aperture in the pre-dawn hours.
Discovered on 1 July 2025 by the ATLAS telescope in Chile, funded by NASA.
Only the third recorded interstellar comet, following 'Oumuamua and Borisov.
NASA confirmed it is a comet, not an alien spacecraft, despite some speculation.
- Who
- NASA, astronomers, and scientists
- What
- Interstellar comet 3I/ATLAS approaching Earth
- When
- Closest approach on 19 December 2025
- Where
- Visible in the east to northeast direction in the pre-dawn hours, under Regulus in the Leo constellation
- Why
- 3I/ATLAS is an interstellar comet passing through our solar system
Scientific Consensus
Alternative Theories
Nature of the Object
Scientific Consensus
NASA and astronomers confirm 3I/ATLAS is a comet with typical cometary features like a coma and tail.
Alternative Theories
Some speculate it could be an alien spacecraft due to its unusual velocity and composition.
Composition and Activity
Scientific Consensus
Scientists attribute the comet's bright green hue and activity to chemical reactions with the Sun.
Alternative Theories
The detection of nickel gas and high velocity fuel speculation about its interstellar origin and unusual composition.
- Comet Name
- 3I/ATLAS
- Closest Approach Date
- 19 December 2025
- Distance from Earth
- 1.8 AU (170 million miles)
- Discovery Date
- 1 July 2025
- Discovery Location
- ATLAS telescope in Chile
- Required Telescope Aperture
- At least 30 centimetres
- Number of Recorded Interstellar Comets
- 3
- Velocity
- 130,000 miles (209,000 kilometres) per hour
- Perihelion Date
- 29-30 October 2025
- Expected Exit from Solar System
- Early 2026
Sources
Interstellar visitor to our solar system, 3I/ATLAS, set to be closest to Earth on 19 December
3I/ATLAS live stream: Here is where to see the comet as it comes near Earth
Earth’s ‘date’ with ‘mysterious’ interstellar comet 3I/ATLAS on Friday
3I/ATLAS Interstellar Comet Heads Towards Earth On December 19: Are We Safe? Check Speed, Distance And More
Interstellar Comet 3I/ATLAS: NASA-Approved Answers To 10 FAQs
3I/ATLAS: Rare interstellar comet passes safely by Earth tonight: When, where and how to watch the historic flyby
