Editing Making A Comet (section)

== What to Say ==

Start by asking if anyone has seen a comet. Show the pictures of various comets on the display board and point out the various features: nucleus, coma, dust tail and plasma tail. Point out in the diagram of the comet orbiting the sun that the tail is always pointing AWAY from the sun. Ask if any of the kids can explain why that is. Likely no one will know why so explain that this demo will help illustrate why that is and what comets are like in general.

Mix the ingredients together and describe what each ingredient represents. The water will represent (once frozen) the ice found in comets, the soil represents the dark organic material, the soy sauce represents the other complex chemicals found in comets, the dry ice represents the frozen carbon dioxide locked into comets and the ammonia is the same as the ammonia found in comets.

After the ingredients have been pressed into a sort of ball, show the comet to the kids and explain that it is similar to the nucleus of a comet.

Use a hot plate to demonstrate the effect of the sun on the “comet”. It should start to evaporate more quickly and create more of a coma. Explain that the sun is really really hot and when a comet gets close to it, it starts to heat up and evaporate. This stuff that's evaporating away is what makes the long tail that you see in pictures.