12月19日，太阳系外天体阿特拉斯（3I/ATLAS）将抵达近地点，迎来观测良机。 阿特拉斯于2025年7月1日由位于智利的巡天望远镜发现。最初，天文学家认为它是一颗长周期彗星，将其编号为C/2025 N1。随着进一步观测，天 文学家确认其轨道是双曲线形状，它是人类迄今发现的造访太阳系的第三颗星际天体，并将其编号修正为3I/ATLAS。 天津市科普作家协会理事、北京天文学会会员刘东宇介绍，截至目前，人类只观测到三颗星际天体，且都是星际彗星。这三颗星际彗星的轨道都 是开放的双曲线，这表明它们穿过太阳系后会离开，不会再次回来。 人类对于星际天体的认识，从经验总结，到理论设想，再到观测验证，经历了数百年的过程。 刘东宇介绍，1609年，开普勒发表"所有行星均围绕太阳做椭圆运动，且太阳处于椭圆的一个焦点上"的观点，即开普勒第一定律；1687年，牛顿 对开普勒第一定律做了进一步证明和完善，并提出天体也可以沿抛物线或双曲线轨道运动。但受限于探测手段，在牛顿提出这一理论的330年之 后，即2017年，人类才观测到第一颗沿双曲线轨道运行的星际天体——奥陌陌。 星际天体，是指不受任何一颗特定恒星的引力约束而在恒星际空间飘荡或在 ...

12月19日，太阳系外天体阿特拉斯（3I/ATLAS）将抵达近地点，迎来观测良机。 阿特拉斯于2025年7月1日由位于智利的巡天望远镜发现。最初，天文学家认为它是一颗长周期彗星，将 其编号为C/2025 N1。随着进一步观测，天文学家确认其轨道是双曲线形状，它是人类迄今发现的造访 太阳系的第三颗星际天体，并将其编号修正为3I/ATLAS。 今年10月29日，阿特拉斯曾抵达近日点，虽然它变得更加明亮，但其角度不利于观测。经过近日点后， 阿特拉斯与地球的距离逐渐缩小，并于12月19日抵达近地点。 "在抵达近地点时，阿特拉斯位于狮子座区域的黄道附近方向，其亮度低于12等，肉眼已无法直接观 察，需要依赖专业的天文望远镜和相机，但这仍不失为人类最后对其进行观测的理想机会。这是因为， 阿特拉斯正以极快的速度飞离太阳系，亮度迅速变暗，直至超出人类探测能力，再也无法被观测 到。"刘东宇说。 天问一号环绕器高分辨率相机拍摄到的阿特拉斯（成像时间10月3日，成像距离约2896万千米）。新华 社发（国家航天局供图） 星际天体，是指不受任何一颗特定恒星的引力约束而在恒星际空间飘荡或在各自轨道上运行的天体，包 括星际小行星、星际彗星和 ...

Core Viewpoint - China's Tianwen-1 orbiter successfully observed the interstellar object ATLAS, marking a significant achievement in space exploration and expanding the capabilities of the Tianwen-1 mission [1][2]. Group 1: Observation Details - The Tianwen-1 orbiter observed ATLAS from a distance of approximately 30 million kilometers, making it one of the closest observations of this interstellar body [1]. - ATLAS was discovered on July 1, 2025, by a telescope in Chile and is the third known interstellar object to visit the solar system [1]. - The object has a hyperbolic trajectory with an eccentricity of 6.23, indicating it does not follow a closed orbit around the Sun [2]. Group 2: Scientific Significance - ATLAS is estimated to be between 3 billion and 11 billion years old, potentially older than the solar system, making it a rare sample for studying the composition of exoplanets and early stellar history [2]. - The ongoing research on ATLAS aims to explore the physical properties and size of the object, which is believed to have a comet-like structure with an icy nucleus [2]. Group 3: Technical Achievements - The Tianwen-1 team began preparations for observing ATLAS in early September, overcoming challenges due to the object's small size (nucleus diameter of about 5.6 kilometers) and faint brightness [3]. - The high-resolution camera on the Tianwen-1 orbiter was utilized to capture images of ATLAS, achieving a significant technical milestone by observing a target that is 10,000 to 100,000 times dimmer than Mars [4]. - The successful observation of ATLAS serves as a technical trial for future asteroid exploration missions, particularly for Tianwen-2 [4].

Core Insights - Elon Musk discussed the scientific community's debate regarding a newly discovered interstellar object, 3I/ATLAS, emphasizing that he would publicly disclose any evidence of extraterrestrial life [3][4] - The object, observed for the first time in July, has a diameter between 440 meters and 5.6 kilometers and is traveling at a speed exceeding 200,000 kilometers per hour, making it the third interstellar visitor observed by humanity [3] - The composition of 3I/ATLAS shows significant differences from known comets, particularly the detection of nickel without the usual accompanying iron, raising questions about its origin [3] - A Harvard astronomer suggested that 3I/ATLAS might not be a naturally formed comet but rather a probe or mothership from an extraterrestrial civilization, calling for more observational data to further research [3] - Musk noted that if the object were primarily composed of nickel, its mass would be enormous, potentially leading to catastrophic consequences if it collided with Earth [3] Summary by Sections - **Interstellar Object Discovery** - 3I/ATLAS is the third interstellar object observed, with a diameter of 440 meters to 5.6 kilometers and a speed over 200,000 kilometers per hour [3] - Its trajectory and material composition differ significantly from known comets, prompting scientific speculation [3] - **Scientific Speculation** - The detection of nickel in the gas cloud surrounding 3I/ATLAS, without the presence of iron, raises questions about its origin [3] - A Harvard astronomer proposed that it could be an artificial object rather than a natural comet, urging for more data to support further investigation [3] - **Musk's Statements** - Musk stated he would publicly announce any evidence of extraterrestrial life and emphasized he would never commit suicide, addressing conspiracy theories about whistleblowers [4] - He highlighted the potential dangers of 3I/ATLAS if it were primarily nickel, suggesting severe consequences in the event of a collision with Earth [3]

Group 1 - The core viewpoint of the article revolves around Elon Musk's comments on the newly discovered interstellar object 3I/ATLAS and the implications of its potential extraterrestrial origins [1][3][4] Group 2 - The interstellar object 3I/ATLAS was first observed by astronomers in July, with an estimated diameter between 440 meters and 5.6 kilometers, traveling at a speed exceeding 200,000 kilometers per hour [3] - The trajectory and material composition of 3I/ATLAS differ from previously observed comets, leading to speculation about its "non-natural origin," with Harvard astronomer Avi Loeb suggesting it could be a "mothership" sent by an alien civilization [3] - Musk acknowledged the presence of nickel in the gas cloud surrounding 3I/ATLAS, noting that many comets and asteroids are primarily composed of nickel, and highlighted the potential catastrophic consequences if such a massive object were to collide with Earth [3][4]

Core Points - Elon Musk discussed the newly discovered interstellar object 3I/ATLAS, suggesting that if evidence of extraterrestrial life is found, he would make it public [1][2] - The object, observed in July, has a diameter estimated between 440 meters and 5.6 kilometers and is traveling at speeds exceeding 200,000 kilometers per hour [1] - There are speculations about the object's "non-natural origin," with Harvard astronomer Avi Loeb proposing it could be a "mothership" sent by an alien civilization [1] Group 1 - The interstellar object 3I/ATLAS is the third observed to visit the solar system, with its trajectory and material composition differing from typical comets [1] - Musk highlighted the presence of nickel in the gas cloud surrounding 3I/ATLAS, noting that many comets and asteroids are primarily composed of nickel [2] - He warned that if the object were entirely made of nickel, it could potentially cause catastrophic damage if it collided with Earth [2] Group 2 - Musk made a public commitment that he would never take his own life, addressing conspiracy theories regarding individuals who know the truth about extraterrestrial life being silenced [2] - The discussion on the podcast included criticism of NASA for not releasing more observational data about 3I/ATLAS [1]

Core Points - The article discusses the recent flyby of the interstellar comet 3I/ATLAS, which poses no threat to Earth as it moves away from the solar system [1][2] - 3I/ATLAS is the third known interstellar object to visit the solar system, following 'Oumuamua in 2017 and 2I/Borisov in 2019 [2] Summary by Sections - **Discovery and Characteristics** - 3I/ATLAS was first reported by the ATLAS survey telescope in Chile on July 1, 2023, and is classified as a comet due to its icy nucleus and coma [1] - The comet's nucleus is estimated to be between 440 meters and 5.6 kilometers in diameter, although its exact size remains uncertain [1] - **Orbital Details** - The comet's perihelion was approximately 1.4 astronomical units (about 210 million kilometers) from the Sun, located inside the orbit of Mars [1] - The closest approach to Earth was about 1.8 astronomical units (approximately 270 million kilometers) [1] - **Significance of the Name** - The name 3I/ATLAS indicates its discoverer (ATLAS team), its interstellar origin (I), and its status as the third confirmed interstellar object [2] - **Scientific Importance** - The ongoing discovery of interstellar objects like 3I/ATLAS aids in understanding the composition of materials outside the solar system, early planetary formation processes, and cosmic physics [2]

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].