Astronomers have just confirmed the discovery of a rare visitor from beyond our solar system — a newly detected interstellar comet. Officially named 3I/ATLAS, the comet was first spotted on July 1 by NASA’s ATLAS survey telescope in Chile.
This is only the third known interstellar object to pass through our cosmic neighborhood, following in the footsteps of 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.
The interstellar comet is currently traveling toward the inner solar system from the direction of the constellation Sagittarius. It’s still more than 400 million miles from the Sun but is expected to reach its closest point—just inside Mars’s orbit—around October 30. Even at its nearest point, though, it poses no threat to Earth.
What makes this object especially exciting is its origin. Unlike typical comets that orbit the Sun, 3I/ATLAS comes from interstellar space. That means it likely formed in a different star system and spent eons drifting between the stars before being captured temporarily by our Sun’s gravity. The ESA also posted about the discovery on Bluesky before it was officially named.
Astronomers may have just discovered the third interstellar object passing through the Solar System! ESA’s Planetary Defenders are observing the object, provisionally known as #A11pl3Z, right now using telescopes around the world.— ESA Operations (@operations.esa.int) July 2, 2025 at 3:23 AM
Since its detection, astronomers have pulled together additional “pre-discovery” images of the interstellar comet, some dating back to mid-June. These images were taken by various observatories, including ATLAS stations worldwide and the Zwicky Transient Facility in California. By combining past and current data, researchers are trying to refine the comet’s trajectory and learning more about its composition.
Studying an interstellar comet like this offers a rare chance to examine the building blocks of planets and stars beyond our solar system. Scientists are racing to gather as much data as possible while it’s still visible to ground-based telescopes. By December, 3I/ATLAS will reappear from behind the Sun, offering a second window for observation.
Its exact size and makeup are still being studied, but researchers are hopeful it will provide new insights into how other planetary systems form and evolve. While these types of visitors are rare, astronomers estimate our solar system could be hiding millions of similar interstellar objects deep in the Oort Cloud that surrounds the solar system.
