Core Points - The interstellar visitor 3I/ATLAS is approaching the Sun and is expected to pass its perihelion around October 29, after which it will gradually move away from the solar system [1][4][7] - 3I/ATLAS was discovered in early July when it was approximately 670 million kilometers from the Sun, traveling at a speed of about 61.3 kilometers per second [4][7] - As it approaches the Sun, its speed has increased to approximately 63.1 kilometers per second, and it is now about 420 million kilometers away [4][7] - By the time it reaches perihelion, its distance from the Sun will shrink to about 200 million kilometers, with a speed of around 68 kilometers per second [7] - The closest approach to Earth will be over 240 million kilometers, posing no threat to the planet [7] - 3I/ATLAS is classified as a comet due to its active nature, with a nucleus diameter estimated to be no more than 5.6 kilometers [10][14] - The brightness of 3I/ATLAS has increased from 18th magnitude at discovery to approximately 16.3, with expectations to reach around 14.3 at perihelion [10] - The scientific value of 3I/ATLAS is significant, providing a unique opportunity to study the composition of exoplanets and the processes of planet formation [14]

Core Viewpoint - The discovery of the interstellar object 3I/ATLAS, the third known visitor to the solar system, has garnered significant attention from astronomers and enthusiasts worldwide [1][4]. Group 1: Characteristics of 3I/ATLAS - 3I/ATLAS is classified as an interstellar object due to its high eccentricity hyperbolic trajectory, with an eccentricity of 6.23, differing from the elliptical or near-parabolic orbits of typical solar system bodies [3]. - The object is believed to have a cold nucleus and exhibits cometary activity, suggesting it is more likely a comet than an asteroid [3]. - At the time of discovery, 3I/ATLAS was approximately 670 million kilometers from the Sun and had a brightness of about magnitude 18, making it difficult to observe with standard telescopes [4]. Group 2: Observational Opportunities and Future Trajectory - Ground-based telescopes are expected to observe 3I/ATLAS until September, after which it will be too close to the Sun for observation [5]. - The object is predicted to reach its perihelion around October 29, entering the orbit of Mars, and will maintain a distance of at least 240 million kilometers from Earth [4]. - Following its perihelion, 3I/ATLAS is expected to gradually move away from the solar system and return to interstellar space over the coming years [5]. Group 3: Historical Context of Interstellar Visitors - Prior to 3I/ATLAS, the first known interstellar visitor was 'Oumuamua, discovered in October 2017, which was initially thought to be an asteroid but later classified as a comet [5]. - The second interstellar visitor, 2I/Borisov, was discovered in 2019 and is also classified as a comet [5]. - The rarity of interstellar objects entering the solar system highlights the unique nature of such discoveries and the ongoing research into their origins [5].