This week, the solar system's elusive innermost planet Mercury is putting on its best appearance of the year in the evening sky. Locating Mercury is one of the sky's great challenges. Even experienced stargazers find locating this small world a difficult task. Tonight, you can end your frustration by using the crescent moon as a pointer to this evasive planet.
During this evening appearance, Mercury will reach it greatest elongation away from the sun on Saturday evening. Mercury, however, will not be alone above the western horizon. It will sit below the crescent moon and just above Mars.
Start your search for Mercury tonight around 6:30. A very thin crescent moon will sit about 12 degrees above the west-southwestern horizon and 4 degrees to the upper right of bright Mercury. Fainter Mars is about 2 degrees directly below Mercury. By Saturday evening, when Mercury reaches greatest elongation, the duo will have separated a little bit as Mercury climbs to about 10 degrees above the horizon.