3I/ATLAS

3I/ATLAS (also designated C/2025 N1) is an interstellar visitor — an object that originated from outside our solar system and is passing through on a one-way trip. It will never return.

The "3I" designation means it's the third confirmed interstellar object ever detected, following:

• 1I/'Oumuamua (2017) — a mysterious elongated object, possibly rocky
• 2I/Borisov (2019) — showed cometary activity
• 3I/ATLAS (2025) — the largest and most anomalous interstellar visitor observed

Every planet, moon, asteroid, and comet in our solar system shares a common origin — the same cloud of gas and dust that formed 4.6 billion years ago.

Several teams have reported molecules like methanol (CH₃OH) and cyanide-bearing species (CN) in its coma. These are common ingredients in prebiotic chemistry—the kind of complex organic building blocks that help scientists study how chemistry varies between star systems.

Interstellar comets are different. They carry material from other star systems, formed under different conditions, possibly billions of years before our sun existed. NASA estimates it may have traveled through interstellar space for about 7 billion years before arriving here.

Studying its composition tells us about the chemistry of distant stellar nurseries — places we can never visit, but whose messengers occasionally pass through our neighborhood.

"These comets are absolutely foreign. Every planet, moon, asteroid, comet and lifeform in our Solar System share a common origin. But interstellar comets are true outsiders, carrying clues about the formation of worlds far beyond our own." — European Space Agency