What is Comet 3I/ATLAS?
Comet 3I/ATLAS is a rare and exciting celestial object—it's an interstellar comet, meaning it originated from outside our solar system, likely from another star system. It's only the third interstellar object ever discovered, following 'Oumuamua in 2017 and Borisov in 2019.
The name "3I/ATLAS" breaks down as follows:
3I: "3I" stands for "third interstellar object."
ATLAS: This refers to the Asteroid Terrestrial-impact Last Alert System, the robotic survey telescope network in Chile that first spotted the object on July 1, 2025.
What makes it so interesting to scientists is its unique chemical makeup and its incredibly high speed, which is evidence that it has been hurtling through interstellar space for potentially billions of years. Its journey through our solar system offers a rare chance to study a pristine sample from a distant planetary system.
When will it arrive?
Comet 3I/ATLAS has already "arrived" and is currently passing through our solar system. It was first discovered on July 1, 2025.
Closest approach to the Sun: The comet will make its closest approach to the Sun (known as perihelion) in late October 2025. At this time, it will be at a distance of about 1.4 AU (astronomical units), which is approximately 130 million miles (210 million km), putting it just inside the orbit of Mars.
Closest approach to Earth: The comet's closest approach to Earth will be in December 2025. At its nearest, it will still be at a very safe distance of about 1.8 AU (170 million miles or 270 million km).
The comet will be difficult to observe from Earth in late September and October as it will pass too close to the Sun, but it's expected to become visible again in early December 2025.
Will it hit Earth?
No, there is absolutely no danger of Comet 3I/ATLAS hitting Earth. Its trajectory and distance have been carefully calculated by astronomers, and it is confirmed to be on a hyperbolic orbit that will take it safely past the Sun and continue its journey out of our solar system, never to return.
