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11-Billion-Year-Old Interstellar Comet Exits Solar System

4/23/2026

Summary

Story summary

Comet 3I/Atlasis may be up to 11 billion years old, making it the oldest known interstellar object.
A University of Michigan team observed the comet as it exited the solar system after passing Earth.
Scientists detected unusually high deuterium in its water, indicating formation in a cold, isolated region before the Sun formed.
The nucleus is estimated between 440 meters and 5.6 kilometers and it is traveling outward at about 137,000 mph beyond Jupiter.

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Story summary

Comet 3I/Atlasis may be up to 11 billion years old, making it the oldest known interstellar object.
A University of Michigan team observed the comet as it exited the solar system after passing Earth.
Scientists detected unusually high deuterium in its water, indicating formation in a cold, isolated region before the Sun formed.
The nucleus is estimated between 440 meters and 5.6 kilometers and it is traveling outward at about 137,000 mph beyond Jupiter.