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].