As the national anthem came to an end before Saturday's Michigan-Purdue game, a message was displayed on the scoreboards about there being a special flyover. The message mentioned that the flyover would be louder than a usual one, and I was pretty confused at the time considering there were no planes or jets in sight.
The reason for this is because the flyover was actually somebody using a jetpack to fly into Michigan Stadium with the game ball. Michigan honored the Apollo 15 crew made up of alumni that went to the moon, and to go along with that the school decided to do the special jetpack flyover.
This was extremely cool to see in person, and yes, it was extremely loud as well.