Back to today’s briefing

Story perspectives

Comet 3I/ATLAS Glows Green as It Exits Solar System

12/18/2025

35 4 Full Breakdown

Summary

Story summary

The interstellar Comet 3I/ATLAS shows changing activity as it exits the Solar System.
Gemini North telescope in Hawaii captured a faint green glow, signaling diatomic carbon gas.
The observations were collected during the 'Shadow the Scientists' outreach initiative with real-time astronomy.
First detected in July 2025, the color changes reflect chemicals evaporating as it heats.

History

Historical Context

Comet Hale-Bopp, discovered independently by Alan Hale and Thomas Bopp on July 23, 1995, became one of the brightest comets in history, peaking in visibility in 1997. Its massive nucleus, estimated at 40 kilometers wide, allowed it to remain visible to the naked eye for 18 months, captivating millions and enhancing our understanding of cometary science and the early solar system.

1 of 2

Story summary

The interstellar Comet 3I/ATLAS shows changing activity as it exits the Solar System.
Gemini North telescope in Hawaii captured a faint green glow, signaling diatomic carbon gas.
The observations were collected during the 'Shadow the Scientists' outreach initiative with real-time astronomy.
First detected in July 2025, the color changes reflect chemicals evaporating as it heats.

1 / 2