Comet 3I/ATLAS

There is an interstellar comet named 3I/ATLAS passing through our solar system right now. This will be its only visit to our solar system because the comet is not tied by gravity to the Sun.

Comet 3I/ATLAS poses no threat to Earth. At its closest approach to Earth on December 19, 2025, the comet will be about 170 million miles away, almost twice as far from us as we are from the Sun.

Although comet 3I/ATLAS appears similar to comets known to belong to our solar system, it has more carbon dioxide and an unusual amount of nickel and iron. This suggests it formed in a solar system different than ours. In fact, the designation “3I” means the comet is the third such object of an interstellar origin.

The comet’s great distance along its path through the solar system makes it too faint to be seen with Griffith Observatory’s telescopes. As a public observatory, our telescopes are optimized for public observing, not the detection of faint objects.

Astronomers around the world are observing this unusual object as it passes through our cosmic neighborhood. That includes space telescopes operated by NASA and other space agencies. To learn more about those observations and the comet itself, check out NASA’s page about comet 3I/ATLAS (https://science.nasa.gov/solar-system/comets/3i-atlas/)

Join us at Griffith Observatory or on the Observatory’s YouTube channel for our monthly All Space Considered program on Thursday, November 20, 2025, at 7:00 p.m., PST, to hear the latest about comet 3I/ATLAS and other news about astronomy and space.