I am sure I said this before but this really was one of my personal favorite actives. It came out amazing and my son loved it. Would for sure do this again.
So it is simply called fizzing planets. You mix a little bit of water in baking soda and add food coloring to color it like the planet you choose. I went by a simple google picture to color the planets and then I realized I got some wrong but we also had a book to look at and read to see some real colors.
Once you make your planets let them cry for a couple of hours. You can place them in the freezer to speed this up.
Then slowly pour vinegar over the planets to see them fizz!
It started to look like a Galaxy then in the end it ended up looking like one big planet.