On the morning of May 9, 2016, the beginning of the day will be cooler than normal. How is it possible to know this? Well the sun's life-giving warmth will be moderated a little bit by the innermost planet Mercury. As the sun rises at 5:30 a.m., the silhouette of Mercury will be seen advancing across the countenance of the Sun. This kind of shadow play by Mercury occurs once every 10 to 12 years. So in the course of a lifetime if you are in the right location and the weather is good there are only a handful of opportunities to enjoy this.