More fun and games for a sunday morning.
It's a remarkable development in the history of astronomy that we now believe most of the Universe comes in "dark" or invisible forms.
So for your scientific enjoyment I include a TED talk on Dark Matter and Dark Energy by particle physicist Patricia Burchat.
I also include a little interactive from McGraw-Hill that will allow you to explore how astronomers conclude that the Universe is full Dark Matter. Make sure you read over the Introduction and How To sections to see how it all works.