Crater brownies

You can get an appreciation of how craters are formed by doing an easy experiment with flour and cocoa powder. You could use instant hot chocolate or any other combination of contrasting powders, but if you use flour and cocoa powder, then you can make delicious desert at the same time.

There are lots of videos that you can watch that explain the experiment. The following video from NASA JPL is a good example – it includes some background information and demonstrates some nice results:

However, one problem with these videos is that they presumably expect you to throw away the materials afterwards. Especially if you’re dropping in stones and household objects. With a little bit of extra effort, you can perform the experiment with recipe ingredients and prevent any waste.

I went with a gluten-free brownies recipe from King Arthur Flour, so that I could share the end result with some coeliacs. It’s mostly sugar, but it has enough flour and cocoa powder for our needs. Measure out the ingredients first, spread the flour evenly in the bottom of a container, and then dust the cocoa powder over the top.

I probably added too much cocoa powder in the top layer. A light dusting is all that you need; so long as you cover the white flour completely. If your container has straight edges, you can use a chopping board to sieve cocoa powder up to the edge without losing any.

Dusting of cocoa powder over a base of flour

Next, you’ll need to select some suitable meteorites. To keep with the edible theme, I chose some small chocolates. They’re not part of the recipe, but you can just pluck them out and eat them as an appetiser.

Selecting meteorites

The following image shows the result from the first few impacts. Not amazing, but there are clear craters and some ejecta – even if the rays are a little difficult to discern. There may have been better results if the flour was deeper. However, since the amount of flour is pre-measured for the recipe, the only way to make it deeper would be to reduce the size of the container.

Example impact craters

After a period of meteorite activity, it’s on to the baking. Strictly speaking, the recipe requires you to add the flour and cocoa powder at different steps, which is tricky after you have mixed them together for the experiment. I just scraped some cocoa powder off of the top for step 3, and then threw in the rest of the flour-cocoa mixture after adding the eggs. It turned out perfectly, so I highly recommend the recipe.

Byproduct of the experiment

Byproduct of the experiment

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