watered down acrylic paints in orange and red (and yellow...)
white paper cut in circles
Pour enough starch in the pie plate to cover the bottom. Drop the paint in to the starch in a random pattern.
Gently place the paper circles into the painted starch and let sit about 30 seconds.
Place somewhere safe to dry (they can stick to the surface so make sure you move them every now and then as they dry to avoid that. Once dry you can place them under a heavy book to flatten out.)
And then you have...
( I did computer edit the background completely out on the pictures....but we glued the planets into black paper frames once they were dry and flat.)