NASA’s ATLAS Telescope Spots Third Interstellar Comet Zipping Through Our Solar System

The Discovery of a Cosmic Wanderer

The NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) survey telescope, located in Rio Hurtado, Chile, made a groundbreaking announcement on July 1, 2025. They reported the initial observations of Comet 3I/ATLAS to the Minor Planet Center. Since this initial report, scientists have pulled together “pre-discovery” observations dating back to June 14 from various ATLAS telescopes worldwide, as well as Caltech’s Zwicky Transient Facility at the Palomar Observatory in San Diego County, California. These earlier sightings helped confirm the comet’s unique nature.

Understanding Comet 3I/ATLAS

Comet 3I/ATLAS now holds the distinction of being only the third known object from beyond our solar system ever discovered. Astronomers have confidently labeled it as “interstellar” because its orbital path is hyperbolic. This means it doesn’t follow a closed orbit around our Sun; instead, it’s merely passing through. By tracing its trajectory backward in time, it’s clear that 3I/ATLAS originated from another star system entirely.

Rest assured, Comet 3I/ATLAS poses absolutely no threat to Earth. It will remain far away, with its closest approach to our planet being approximately 1.8 astronomical units (about 170 million miles, or 270 million kilometers). The comet is projected to reach its closest point to our Sun around October 30, 2025, at a distance of about 1.4 AU (130 million miles, or 210 million kilometers) – a path that keeps it just inside the orbit of Mars.

Scientists globally are currently investigating the interstellar comet’s exact size and physical characteristics. 3I/ATLAS is expected to stay visible to ground-based telescopes through September 2025 before it gets too close to the Sun for observation. It will re-emerge for renewed study by early December 2025, appearing on the other side of the Sun.

What’s in a Name? The Meaning Behind 3I/ATLAS

Typically, comets are named after their discoverer(s). In this case, the ATLAS survey team gets the credit. The letter “I” stands for “interstellar,” clearly indicating that this cosmic visitor originated from outside our solar system. The “3” in its name denotes that it’s the third interstellar object ever confirmed.

Frequently Asked Questions About 3I/ATLAS

Where did this interstellar object come from?

3I/ATLAS formed in another star system and was somehow launched into interstellar space – the vast emptiness between stars. For millions, possibly even billions of years, it has been drifting through the cosmos until its recent arrival in our solar system. It was detected approaching from the general direction of the constellation Sagittarius, which is where the central region of our Milky Way galaxy is located. When first spotted, 3I/ATLAS was approximately 410 million miles (670 million kilometers) from the Sun, putting it within Jupiter’s orbit.

How was it determined that 3I/ATLAS didn’t originate in our solar system?

Observations of the comet’s path show it’s moving too fast to be held by the Sun’s gravitational pull. It’s on what’s known as a hyperbolic trajectory, meaning it won’t follow a closed orbital path around our Sun. It’s simply passing through and will continue its journey into interstellar space, never to return.

How many interstellar objects have been discovered so far?

This is the third confirmed interstellar object observed. The first, ‘Oumuamua, was discovered in 2017, followed by 2I/Borisov in 2019.

How big is 3I/ATLAS, and is it an asteroid or a comet?

Astronomers don’t yet know its exact size. However, observations confirm it’s “active,” meaning it has an icy nucleus and a coma – a bright cloud of gas and dust that forms around a comet as it nears the Sun. This activity is why it’s classified as a comet, not an asteroid.

How fast is it moving?

It’s moving incredibly fast! When first discovered, this interstellar comet was traveling at roughly 137,000 miles per hour (221,000 kilometers per hour, or 61 kilometers per second). Its speed will only increase as it approaches the Sun.

Is there a danger of this interstellar object hitting Earth?

No. While its trajectory brings it into the inner solar system, it won’t come anywhere near Earth. As Comet 3I/ATLAS continues its journey, it will not come closer than 1.6 AU (about 150 million miles, or 240 million kilometers) to our planet.