谷神星今年冲日是在10月8日，位于鲸鱼座，最大亮度7.6等。"冲日前后几天，太阳落下以后，谷神星 就会从东方地平线上升起，直到第二天太阳升起后，它才从西边落下，因此整夜均可观测。"赖迪辉 说。 中国天文学会会员、天津市天文学会理事赖迪辉介绍，绝大多数小行星位于火星和木星轨道之间的小行 星带内。本次冲日的主角谷神星是人类发现的第一颗小行星。随着矮行星定义的公布，谷神星被归类为 矮行星，于是它就成为现在太阳系中最小的、也是唯一位于小行星带中的矮行星。 这张由美国国家航空航天局2014年1月22日提供的概念图显示的是谷神星位于火星和木星轨道间的小行 星带中。新华社/路透 谷神星的公转周期4.6年，会合周期467天，也就是大约1年又3个多月冲日一次。谷神星冲日是指谷神 星、地球与太阳呈近似一条直线，地球位于两者之间。此时，谷神星被太阳照亮的一面会完全朝向地 球，其亮度会达到最高值。 太阳系中最小的矮行星——谷神星将于10月8日冲日，迎来观测良机。天文科普专家表示，冲日前后几 天，感兴趣的公众借助小型天文望远镜或双筒望远镜，有望在秋季夜空中找到谷神星的身影。 这是2015年3月1日从"黎明"号小行星探测器上拍摄的谷神星 ...

Core Points - The article discusses the phenomenon of Pluto's opposition, which occurs when Pluto is closest to Earth and at its brightest, making it an ideal time for observation [1][4] - It explains the definition of Pluto's opposition and its significance in astronomy, including the alignment of Pluto, Earth, and the Sun [4] - The article also covers the historical context of Pluto's discovery and its reclassification from a planet to a dwarf planet by the International Astronomical Union in 2006 [10][13] Summary by Sections Pluto's Opposition - Pluto's opposition occurs when it is positioned 180 degrees from the Sun, allowing for optimal visibility from Earth [4] - The specific timing of this year's opposition is noted to be around 14:30 Beijing time on July 25 [4] - During this event, Pluto rises in the east at sunset and sets in the west at sunrise, making it visible almost all night [4] Distance and Visibility - Even at its closest approach on July 22, Pluto is still approximately 34.3 astronomical units away from Earth, which is 34.3 times the distance from Earth to the Sun [7] - The brightness of Pluto during opposition is about 1/1200th of what is seen from Earth, making it appear as a faint star [7] - Observing Pluto requires a telescope with an aperture of at least 20 centimeters, as it appears as a small white dot similar to a regular star [7] Historical Context - Pluto was discovered in 1930 by Clyde Tombaugh and was initially classified as the ninth planet in the solar system [10] - Its diameter is approximately 2,370 kilometers, which is smaller than both Earth and the Moon [10] - The discovery of other similar celestial bodies led to a reevaluation of the definition of a planet, resulting in Pluto's reclassification as a dwarf planet in 2006 [10] Future Exploration - Despite its reclassification, Pluto remains a subject of interest, especially after the New Horizons spacecraft's flyby in 2015, which provided valuable data and images [13] - Pluto's largest moon, Charon, has a diameter of about 1,200 kilometers, and its presence complicates early observations of Pluto [14] - Advancements in technology may lead to more missions aimed at further exploring Pluto and its mysteries [14]

Core Insights - A team of Chinese researchers from Princeton University has discovered a new celestial body in the outer solar system, which is likely a dwarf planet [1][2] - The discovery challenges the existence of the hypothesized ninth planet due to the stability of the newly found object [2] Group 1: Discovery Details - The newly identified celestial body is named 2017 OF201, with a diameter of approximately 700 kilometers [2] - It orbits the Sun in a highly elliptical path, taking about 24,000 years to complete one orbit, with its aphelion exceeding 1,600 astronomical units [2] - The discovery was driven by a desire to find a large and distant object, following a hypothesis about the existence of a ninth planet [1][2] Group 2: Implications of the Discovery - The existence of 2017 OF201 raises questions about the stability of the hypothesized ninth planet, as it should have been ejected from its orbit if the ninth planet were present [2] - The researchers' findings suggest that if 2017 OF201 remains in its current orbit, it indirectly indicates that the ninth planet may not exist [2] - The discovery is significant as it represents the farthest celestial body identified by Chinese researchers in the solar system [3]

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]