An interstellar comet will reach its closest point to the sun this week. Don't worry, it won't even come close to Earth.

An interstellar comet that entered our solar system for a brief visit this year has captivated the attention of astronomers from around the world. Comet 3I/ATLAS is the third known interstellar object ever detected passing through our solar system, according to NASA.

The comet was first discovered on July 1, 2025, by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescope located in Rio Hurtado, Chile.

Astronomers were able to look back at telescope archives and found that the comet had been observed as far back as June 14. Observations from the Hubble Telescope indicate that the comet’s nucleus is no smaller than 1,444 feet and isn’t bigger than 3.5 miles.

Here’s what else we know about the interstellar object.

Why is it classified as a comet?

Using powerful telescopes, astronomers have been able to observe that the comet is made of ice and also has a bright cloud of gas and dust around it, called the coma. As a comet approaches the sun, its ice and dust start to vaporize, which is why it will appear fuzzy or will have a tail.

Astronomers believe that the comet was likely formed billions of years ago, which could make the lone traveler older than our own solar system.

How did the comet get its name?

Comet 3I/ATLAS follows in the cosmic footsteps of 1I/’Oumuamua in 2017 and 2I/Borisov in 2019, which are all objects from outside of our solar system.

The “3I” means that it’s the third interstellar object discovered within our solar system. “ATLAS” indicates which astronomical survey was responsible for discovering it.

How do scientists know the comet isn’t from our solar system?

The comet is on what’s known as a hyperbolic trajectory, which means that it doesn’t follow an orbital path around the sun. It’s also traveling at about 137,000 miles per hour, which is too fast for the comet to be slowed down by the sun’s gravity.

Is this interstellar comet a threat to Earth?

No. Even though the comet is in our solar system, it won’t even come close to Earth. In fact, NASA says the comet won’t come any closer than 170 million miles to our planet.

What is the comet’s path?

Comet 3I/ATLAS is rapidly approaching the sun, with its closest approach on Oct. 30, just inside the orbit of Mars, according to NASA. By early December, it will reappear on the other side of the sun, but it won’t be able to be seen without a telescope.

What have astronomers learned from the comet so far?

An interstellar object is so valuable for the scientific community because it acts like a cosmic time capsule that could hold other chemical and physical information about other star systems where it was formed, potentially billions of years ago.

Astronomers said they have unexpectedly detected atomic nickel vapor from the comet at a vast distance from the sun, where temperatures are extremely cold (about four times Earth's distance from the sun). When temperatures are extremely cold, it’s hard for solid metal like nickel to turn directly into vaporized gas.

Astronomers have been intrigued by how the nickel could be vaporizing at such low temperatures. They believe it's possible that the nickel is attaching to carbon monoxide or other organic compounds, “which can release nickel atoms at much lower temperatures than would be needed for metal to vaporize directly,” according to Space.com.