Active object · Watching
3I/Atlas — third interstellar object on record
An interstellar comet detected in 2025, currently transiting the inner solar system. The Council is monitoring after a reported anomalous brightening on 23 April 2026.
Right ascension
2026-04-2614h 32m 18s
Declination
2026-04-26-08° 14′ 06″
Apparent magnitude
2026-04-2614.6
↑ from 15.2 on 21 Apr
Distance from Earth
2026-04-262.41 AU
361,000,000 km
Heliocentric velocity 41.2 km/s
Designation 3I/Atlas
Status Watching
Council case #00482
What the Council is watching for
Three classes of evidence will move our verdict on 3I/Atlas off "Watching":
- Spectroscopy. Gas emission lines would confirm cometary activity and resolve the brightening event as a natural outburst.
- Polarimetry. The polarization signature distinguishes dust scattering from other sources of light.
- Non-gravitational acceleration. Any deviation from a purely gravitational orbit fit would itself be significant; outgassing is the standard explanation, but the magnitude matters.
Observation guidance
At magnitude 14.6, 3I/Atlas is below naked-eye and binocular limits. An 8-inch (203 mm) or larger telescope on a tracking mount is required. The Council's recommended consumer scope for this object is the Celestron NexStar 8SE; finder charts will be published in tomorrow's brief.
Related
Active case file: Case #00482 — Anomalous brightening event of 23 April 2026.