8月"星空剧场"又上新了。19日，水星将迎来西大距。天文科普专家表示，今年水星共有3次西大距，本月的西大距是观测条件最好的一次。在本 次大距前后的几天清晨，如果天气晴好，感兴趣的公众有望一睹这颗贴近太阳、平时难得一见的行星。 在肉眼可见的太阳系5颗行星中，水星是最难观测的一颗。主要原因在于，水星是距离太阳最近的行星，从地球上看，它和太阳也是挨得很近，几 乎与太阳同升同落，常被太阳的光掩盖。 那么，什么时候可以观测水星？"在一个会合周期（约116天）里，从地球上看，当水星与太阳的张角最大，即'大距'时，是观测水星的最佳时 机。大距分为东大距和西大距。东大距前后，水星在黄昏时分的西方低空出现；西大距前后，水星在黎明时分的东方低空出现。"中国天文学会会 员、天津市天文学会理事杨婧说。 2022年10月9日水星西大距，这是10月10日凌晨在天津东丽区吉兆桥拍摄的水星。（杨婧 摄） 水星运行速度很快，围绕太阳运动一周仅需88天，因此，一年当中水星东大距和西大距会各出现3至4次。每次大距时，水星的观测条件也不一 样，这是水星和太阳的位置关系变化所造成的。 杨婧同时表示，观测水星不限于19日。前后几天，水星的高度变化不大， ...

新华社天津8月17日电（记者周润健）8月"星空剧场"又上新了。19日，水星将迎来西大距。天文科普专 家表示，今年水星共有3次西大距，本月的西大距是观测条件最好的一次。在本次大距前后的几天清 晨，如果天气晴好，感兴趣的公众有望一睹这颗贴近太阳、平时难得一见的行星。 在肉眼可见的太阳系5颗行星中，水星是最难观测的一颗。主要原因在于，水星是距离太阳最近的行 星，从地球上看，它和太阳也是挨得很近，几乎与太阳同升同落，常被太阳的光掩盖。 水星运行速度很快，围绕太阳运动一周仅需88天，因此，一年当中水星东大距和西大距会各出现3至4 次。每次大距时，水星的观测条件也不一样，这是水星和太阳的位置关系变化所造成的。 "本次大距观测条件不错，日出时水星的地平高度约18度，亮度0等。有条件的公众如果借助天文望远镜 观测，还会发现水星呈月牙形，约40%的圆面被太阳照亮。"杨婧说。 杨婧同时表示，观测水星不限于19日。前后几天，水星的高度变化不大，都有机会观测到。（完） 那么，什么时候可以观测水星？"在一个会合周期（约116天）里，从地球上看，当水星与太阳的张角最 大，即'大距'时，是观测水星的最佳时机。大距分为东大距和西大距。东大距 ...

Core Points - Mercury will have its eastern elongation on July 4, 2023, providing good observation conditions for the public if the weather is clear [1][2] - Mercury is the closest planet to the Sun and is difficult to observe due to its proximity to the Sun's glare [1] - The best time to observe Mercury is during its eastern elongation when it appears in the western sky after sunset [1] Observation Conditions - This year, Mercury will have three eastern elongations, occurring on March 8, July 4, and October 30, with the first two having favorable observation conditions [2] - On July 4, Mercury's altitude will be approximately 18 degrees at sunset, with a brightness of about 0.4 magnitude [2] - Observers are encouraged to look for Mercury a few days before and after July 4, as the altitude will be higher in the days leading up to the event [2]

Group 1 - The event of Mercury accompanying the Moon on June 27 is highlighted as a noteworthy astronomical occurrence, with favorable observation conditions [1][2] - Mercury is the smallest planet in the solar system and is often difficult to observe due to its proximity to the Sun, only becoming visible during its greatest elongation, known as "greatest distance" [1][2] - This month, Mercury appears as an "evening star" after sunset, positioned in the northwest sky, while the crescent Moon will accompany it, creating a rare "star-moon dialogue" [2] Group 2 - The concept of "greatest distance" is explained, with distinctions made between eastern and western greatest distances, affecting visibility during dawn and dusk [2] - Observers are encouraged to use binoculars or small telescopes for better viewing of the Mercury-Moon conjunction, and astrophotographers are advised to capture this unique moment [2] - The nearby Beehive Cluster, a loose star cluster, can also be observed, although it may be challenging due to the remaining daylight [5]