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 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 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].

Core Viewpoint - A new comet named SWAN is rapidly approaching the Sun, expected to reach its closest point to the Sun on May 1, with an estimated brightness of around magnitude 7 [1][3]. Group 1: Comet Characteristics - The SWAN comet was first observed by the SWAN camera on the European Space Agency's SOHO spacecraft in late March and was officially named "C/2025 F2 (SWAN)" by the International Astronomical Union on April 10 [1][2]. - The comet has a parabolic orbit with an eccentricity of 1.0000995, indicating it will not return after its close approach to the Sun [1][2]. - SWAN is characterized by its green appearance due to diatomic carbon in its coma, which reflects sunlight [2]. Group 2: Observational Details - The comet is currently moving from the northern hemisphere towards the southern hemisphere, with its closest approach to the Sun occurring at approximately 50 million kilometers, within the orbit of Mercury [2]. - It is expected to be observable from the northern hemisphere until around May 8, after which it will become increasingly difficult to see as it moves southward [2]. - There is uncertainty regarding the comet's stability as it approaches the Sun, with potential for disintegration due to solar heat, which has already been observed to some extent on April 20 [2]. Group 3: Public Observation - If the SWAN comet survives its close approach, it can be observed using binoculars or telephoto lenses in early May after sunset [3]. - The public is encouraged to check for the latest updates on the comet's status as it approaches the Sun [2].