Make a comet, two ways

We talked about comets, meteors, and asteroids, and found two fun ways to model a comet. (We also considered making these edible asteroids, but didn't end up doing it.) 

The first comet uses dry ice, and we had done this before, but it is always fun to play with dry ice! We got the recipe here. These comets are basically made of the same things real comets are made of!

You need the following ingredients:
2 cups water
2 cups dry ice
2 tablespoons sand or dirt
A dash of ammonia
A dash of organic material (dark corn syrup works well)

You can find more instructions at that link, but basically you mix those things together and freeze them into a sort of ice ball. Then you can set it in the sun and watch the ice sublimate and form little trailing "tails." It's really cool!

You can see the gases trailing off our "comet" in this video.

I think the children had even more fun, though, with this second comet-making activity, which is basically homemade ice cream in a bag! We used to do this at Girls' Camp when I was young, but my kids have never done it before and they were AMAZED when they opened up their ziploc bags and there was ice cream inside!

The instructions are here (the second recipe on the page) along with an explanation of why this is a valid model of a comet. :)

I love Teddy's face as he bites into his ice cream.

And Daisy's wide eyes! :) Such a fun activity.

Making a comet

My parents were always up on the latest astronomical happenings, so I saw lots of comets as I was growing up---I still remember getting out of the car by Utah Lake in the cold and dark of night, peering up at the sky with binoculars too big for my face, trying to see Halley's Comet. (I never did get a very good look at it. And it isn't going to come around again till I'm 82!) My brothers and I were marched outside night after night to follow the progress of Comets Hale-Bopp and Hyakutake as well. So I have a soft spot in my heart for comets.

We found several tutorials online for how to make your own "comet." Any day we get to use dry ice is a good day, so we gave it a try. It was fun to see the comet sublimating into the air and making icy trails as the heat of the hair dryer hit it!

This one didn't hold together very well. Perhaps our dry ice wasn't old enough (we didn't keep it overnight, as the instructions suggest). Still, we could observe pitting and sublimation at work.

This one was better. Here, we observe what happens when it's hit with "Solar wind"