I’m fascinated by rare astronomical events such as the upcoming Transit of Mercury. From earth, proper instruments can track the movement of the small planet across the surface of the sun. The event that occurs 13 times per century is not visible to the naked eye without serious damage. Better to watch the live streaming on Monday morning, 9 May.
Even more spectacular was the Transit of Venus that occurred in 1882, 2004, and 2012. I mentioned it on my Facebook page at the time. John Phillip Sousa, also intrigued by astronomical phenomena, composed The Transit of Venus March in 1882.