星空有约｜水星4日迎来年度第二次东大距，观测条件不错

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]