1) Colour in the Sun, Moon and Earth and then cut out both circles along the outer line.
2) Cut out the three grey areas of the top wheel (the one containing the Sun).
3) Pierce a hole through the wheels on the cross mark.
4) Then place both pieces on top of each other (with the one that contains the Sun and Earth and the top) and affix with a split pin or pin (through the hole at the centre).
When finished, you will have to hold the wheel from the sun picture while turning the bottom wheel to reveal 'solar eclipse' and 'lunar eclipse'.