Create the inner and outer core. Place one of the cherry sour candies, which will represent the dense inner core, on the end of a toothpick. Heat up the caramel until it is soft and dip the cherry sour into it. This caramel coating represents the more malleable outer core. Briefly dip the caramel-covered cherry sour into ice water to help it cool quickly and then redip it into the caramel. Repeat this process until the resulting ball is roughly twice as large as the original cherry sour, since the inner and outer cores are roughly similar in thickness.
Create the mantle using ice cream. Scoop out a large chunk of vanilla ice cream and push the caramel-covered cherry sour into the center of it. Using your fingers, sculpt the ice cream into a large ball that more than twice the size of the caramel-covered cherry sour, as the mantle is the thickest layer of the earth. Remove the toothpick and place the ball in a freezer.
Place about 2 cups of chocolate chips in a sauce pan (amount will vary by pan size) and heat on low, stirring frequently with a rubber spatula, until melted.
Create the earth's crust. Remove the ice cream ball from the freezer and drizzle the melted chocolate over it until it is coated in a very thin layer. This represents the crust, which is just a hair's thickness in comparison with the other layers of the earth. Return to the freezer for at least two hours to allow it to fully solidify.
Take the model of the earth out of the freezer when it is ready to be eaten. Place it on a cutting surface and slice it down the middle so that all the layers are showing.