Pour flour and water into a pot.
Simmer the mixture for three minutes.
Remove the pot from the heat. Allow it to cool.
Tear or cut newspaper into strips.
Blow up 10 balloons. Blow up one of the balloons very large. This will be the sun. Blow up four of the balloons medium-sized. These will be Jupiter, Saturn, Neptune and Uranus. Blow up four of the balloons smaller-sized. These will be Mercury, Venus, Earth and Mars. Blow up that last balloon very small. This will be Pluto.
Submerge the strips of newspaper in the flour paste.
Cover each of the balloons with five layers of flour paste-soaked newspaper strips.
Allow the balloons to dry until they are hard. This can take up to three hours.
Use a pin to pop the balloons inside the papier-mache shells.
Paint the outside of the balloons with tempera paint to match their corresponding celestial bodies. Allow the paint to dry completely.
Bend a wire coat hanger so that it is shaped like a circle.
Apply a dollop of hot glue to the top of each celestial body.
Place the end of the short pieces of twine on each celestial body. Allow the hot glue to cool completely.
Tie the open ends of the twine attached to planets to the coat hanger circle. Make sure to place the planets in the right order.
Attach the three longer pieces of twine to the coat hanger, spacing them out evenly.
Tie the open ends of the three longer pieces of twine together.
Apply a dollop of glue on the open end of the twine attached to the sun, and press the glued end to the middle of the three longer tied ends. Allow the glue to cool completely.
Hang up the mobile by the tied ends, which will allow the sun to hang down in the middle of the ring of planets.