Core Viewpoint - The C/2025 A6 (Lemmon) comet, with a 1300-year orbital period, has gained public attention as it approaches its perihelion, providing a rare opportunity for observation in various regions of China during dawn and dusk [1][4]. Group 1 - The Lemmon comet is expected to pass its perihelion on November 8, 2025, and will be visible in the early morning and evening skies in most parts of China [1][4]. - The comet is likely a long-period comet originating from the Oort Cloud, which contains billions of primitive small celestial bodies [2][3]. - Initial brightness expectations for the comet were low, but it has exceeded these expectations since early July, leading to increased global interest and successful observations by astronomy enthusiasts [4]. Group 2 - The comet's nucleus appears green with a long, pale blue tail, making it visually distinctive [4]. - Observers in the northern hemisphere can see the comet in the eastern sky before sunrise until October 20, after which it will be visible in the western sky after sunset [4]. - Visibility of the comet will vary slightly by region, and it will become increasingly difficult to observe after its perihelion [4].

Core Points - A potential dwarf planet named 2017 OF201 has been discovered beyond Neptune, challenging the existence of hypothetical celestial bodies like "Planet Nine" [1][2] - The discovery was made by researchers at Princeton University using data from the Victor M. Blanco Telescope in Chile, with 2017 OF201 having a diameter of approximately 700 kilometers, making it comparable to Pluto [1] - The orbit of 2017 OF201 is significantly distant, currently about 90.5 astronomical units (AU) from Earth, and it has a perihelion of 44.5 AU and an aphelion of 1600 AU [1][2] Group 1 - The orbit of 2017 OF201 does not conform to the patterns observed in other extreme trans-Neptunian objects (TNOs), which some researchers believe could indicate the presence of "Planet Nine" [2][3] - Simulations suggest that if "Planet Nine" exists, 2017 OF201 would be ejected from the solar system over millions of years, indicating that its existence does not support the hypothesis of "Planet Nine" [3] - The upcoming Vera C. Rubin Observatory in Chile is expected to enhance the search for similar celestial bodies, potentially providing more insights into the existence of "Planet Nine" [4]

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].