A small red/orange sphere appeared in the sky, moved in closer and got bigger over the city of Green Bay, and vanished leaving a trail.While enjoying the fireworks on a hill showing the entire city of Green Bay, I noticed a small red/orange sphere in the sky that I initially assumed was another firework. However, it didn't explode; it only got closer and bigger. In an instant it was over the city of Green Bay, moving very slowly for a few seconds, before trailing off and out of sight. My entire group of friends sitting with me was silent for a few seconds before one asked "Did anyone else see that?” He was immediately met with agreement from the whole group. The whole event couldn't have lasted over 20 seconds