Timeline
Follow the journey of Comet 3I/ATLAS from its discovery through its passage of our solar system. Track key events, observations, and scientific milestones.
Comet 3I/ATLAS discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile.
Key Details:
- • First detected as a fast-moving object with unusual trajectory
- • Initial magnitude approximately 13.2
- • Designated as potentially interstellar based on orbital characteristics
Gemini North and other major observatories begin systematic observations.
Key Details:
- • Spectroscopic analysis reveals CO₂-dominated coma
- • Nucleus size estimated between 0.32-5.6 km
- • No significant water ice detection in early observations
Comet shows increased activity as it approaches the Sun, developing visible coma.
Key Details:
- • Magnitude brightened to ~12.5
- • Coma diameter increased to ~30 arcseconds
- • Possible green coloration detected in some images
3I/ATLAS reaches its closest point to the Sun at 1.36 AU.
Key Details:
- • Closest approach to Sun: 1.36 AU
- • Expected maximum activity and brightness
- • Optimal period for spectroscopic studies begins
Comet reaches peak apparent magnitude, estimated around 11.5-12.0.
Key Details:
- • Peak magnitude expected: 11.5-12.0
- • Best photographic opportunities
- • Tail development may be visible
3I/ATLAS makes its closest approach to Earth at 1.8 AU (270 million km).
Key Details:
- • Minimum distance: 1.8 AU (270 million km)
- • Best observing geometry for detailed studies
- • Optimal time for amateur observations
Comet begins to fade as it moves away from the inner solar system.
Key Details:
- • Activity decreases as distance from Sun increases
- • Magnitude drops below 13.0
- • Last opportunities for detailed observations
Last observations before 3I/ATLAS becomes too faint for most telescopes.
Key Details:
- • Magnitude drops below 14.0
- • Only large telescopes can track the comet
- • End of amateur observation period
This timeline tracks the key events in the observation and study of Comet 3I/ATLAS. Dates marked as "upcoming" are predictions based on current orbital calculations and may be updated as new data becomes available.
Sources include official announcements from space agencies, peer-reviewed research, and observations from professional and amateur astronomers worldwide.