星空有约｜水星又要“露脸”了，机会难得

Core Points - Mercury will have its best observation opportunity during the western elongation on August 19, 2023, with favorable conditions for the public to view the planet if the weather permits [1][4] - Mercury is the hardest planet to observe due to its proximity to the Sun, often being obscured by sunlight [2] - The best time to observe Mercury is during its greatest angular distance from the Sun, known as "greatest elongation," which occurs approximately every 116 days [2][4] Observation Conditions - This western elongation will allow Mercury to be seen in the eastern low sky during dawn, with a horizon height of about 18 degrees and a brightness of 0 magnitude [4] - Observers using telescopes may also see Mercury in a crescent shape, with approximately 40% of its surface illuminated by the Sun [4] - The observation opportunity is not limited to August 19; several days before and after also provide chances to view Mercury due to minimal height variation [7]