3I/ATLAS is performing it's closest approach to Mars - the red planet - today October 3rd, just a couple days after a US government shutdown has paused the majority of activity for important US government science agencies such as NASA.
Will we still get the imagery of interstellar object 3I/ATLAS that we hoped for? Did 3I/ATLAS survive the CME impact? Latest imagery and updates provided by geophysicist Stefan Burns.
3I/ATLAS, also known as C/2025 N1 (ATLAS) and previously designated A11pl3Z, is an interstellar comet discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) at Río Hurtado, Chile. It’s the third confirmed interstellar object to pass through our solar system, following 1I/ʻOumuamua (2017) and 2I/Borisov (2019).
Here’s a concise overview based on available data Trajectory and Speed: 3I/ATLAS follows a hyperbolic orbit, not bound to the Sun, with an eccentricity of 6.14, indicating its interstellar origin. It was traveling at ~61 km/s when discovered and will reach a maximum speed of 68.3 km/s at perihelion (closest approach to the Sun) on October 29, 2025, at 1.36 AU (203 million km), between Earth and Mars orbits. Its closest approach to Earth will be 1.8 AU (270 million km) in December 2025, posing no threat.
Physical Characteristics: It’s an active comet with a coma (a cloud of gas and dust) and a possible tail, suggesting a nucleus rich in volatile ices like water, with potential for carbon dioxide and monoxide. The nucleus size is uncertain, estimated between 0.32–5.6 km by Hubble, with some sources suggesting up to 10–20 km, larger than ʻOumuamua . Its reddish hue and spectral data hint at complex grain sizes or unique composition, possibly from the Milky Way’s thick disk, suggesting an age of at least 7 billion years, older than our solar system.
Scientific Significance: As a rare interstellar visitor, 3I/ATLAS offers insights into the chemistry and formation of distant star systems. Its early detection allows extended observation compared to its predecessors. Telescopes like Hubble, James Webb, and Vera C. Rubin Observatory are studying it, with data showing water ice and vapor. Its trajectory from the Milky Way’s thick disk suggests it’s a pristine relic from an ancient stellar environment.
Observability: Currently at magnitude ~18, it’s too faint for naked-eye viewing, requiring a 6–16-inch telescope with CCD imaging. It may brighten to magnitude 11 by perihelion, becoming accessible to advanced amateur astronomers. It’s visible in the evening sky (Sagittarius/Libra) until September 2025, then lost in the Sun’s glare during perihelion, reappearing as a morning object (Virgo/Leo) by November–December 2025.
Speculation on Alien Technology: Some, like Avi Loeb, have raised the possibility of 3I/ATLAS being an alien probe due to its anomalous traits, as with ʻOumuamua. However, most astronomers attribute its behavior to natural cometary activity, with no evidence of non-gravitational acceleration or technosignatures.
Future Study: Observations continue, with James Webb Space Telescope scheduled for August and December 2025 to analyze its composition. The ESA/JAXA Comet Interceptor mission (launching 2029) may target similar objects, but 3I/ATLAS’s speed makes a dedicated mission unlikely.