30+ lights traveled low and silent over the city and a silent triangle shape with no belly strobe flew directly overhead.We were in the Bellevue Wisconsin Home Depot parking lot putting our purchases into the truck when we saw 5 lights in the west flying in kind of a v or check mark formation. My husband is a pilot and so of course interested in planes, we thought the formation was probably some kind of military planes or helicopters and we stopped to watch it. We quickly noticed that there was no noise, if these were military jets or helicopters we would be able to hear them a good distance away, but there was no sound. As we continued to watch, the lights did not change in size though they did move from the west and then turned to the north. Behind these initial 5 came more and more, single file low over the city and then they would turn north and continue until they were out of our site. These lights were not perfectly spaced, but they came one after another and we could see them coming from some distance away. It was not like these were just coming up over a building into sight; we could see them far in the distance come closer in a straight line, then turn north and eventually out of sight. We did not keep an exact count, and as some would go out of sight we could see more coming, but we saw at a minimum 30, more likely 40 of these yellowish round non blinking lights move across the sky. The sky was clear, mostly dark with the west horizon still reddish from the sun set, but stars were visible in the sky. As we were standing there watching the lights, we noticed a light in the sky moving toward us from NW to SE. As we looked at it we could tell that it was triangle shaped, but it was not airplane shaped. We could not see stars behind it, it blocked the sky in a full triangle shape. My husband being a pilot immediately noticed that while it did have blinking lights at the three triangle points, there was no belly strobe. We could see the blinking belly strobe on other airliners high in the sky but not on this. Whatever was flying over us was large, completely silent and flying very slow and low. My husband estimates that the aircraft was flying approximately 3000 feet off the ground, well less than 5000 ft.Our background: We are both in our 40’s, employed full time in white collar jobs, we have two children ages 10 and 12, we were completely sober, not a drop to drink that night. My father is a very active private pilot, and while my husband does not have a current license he graduated from the North America Institute of Aviation in Las Cruces, NM in May 1991 with his Commercial Pilot license and CFI rating. We are both familiar with aircraft and whatever we saw that night, we cannot explain. This was the most bizarre experience we have ever had. When the lights stopped, we got in the truck to drive home and I immediately called my dad (8:49pm CST) to see if he knew of any kind of aviation event going on in the area that might explain what we saw, but he did not. When we got home I called the news stations (WBAY 920-438-3264 at 9:06pm) (WFRV 800-236-5550 9:11pm) (WLUK 920-490-1407 9:28pm) and while no one knew what we saw, we were not the only ones who called. The news stations said they had received multiple calls and it seems they were all from the same Bellevue/East Green Bay area we were in. I called the Green Bay non emergency police number (920-391-7450 9:13pm). While talking to the woman who answered my call, she said she needed to put me on hold for 911, I thought she was transferring me to 911 so I hung up. A few minutes later (9:18pm) my phone rang, and it was the police calling me back, she explained that she had to put me on hold so she could take a 911 call. She completed taking my information and! said they would get in contact with the airport and investigate. I asked if it was possible to get any follow-up as I would love to have an explanation for what we saw, but she said she transferred the information to her supervisor and she would not know the outcome. So far we have seen nothing in the news regarding what we saw, but we would love an explanation.