I don't know a museum can be that crowded even at ...

I don't know a museum can be that crowded even at night. I visited in an evening in October when I visited SF. Exploratorium was full of people. I can't find a locker. I was very tried that day and was only spent some time on the SOUND part. It is overall a very interactive experience to learn some 'common' and 'uncommon' things. By the way, they provide food and wine at night.