星空有约｜25日冥王星冲日！迎来观赏期

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]