what good invention could a nine year old do for the planet pluto?

Answer 1

How about a demonstration of the brightness and warmth of the Sun as seen from Pluto. The Sun shines 1,366 watts of light on every square meter on Earth. But Pluto is 40 times as far from the Sun so it gets only 1/40 squared or only 1/1,600 as much light from the Sun. That is only 0.85 watts per square meter. So light from a 60 watt bulb spread out over 70 meters would be about that bright. I calculate that sphere of 2.37 meters radius has that area. He or she could set up a 60 watt light bulb 2.37 meters (almost 8 feet) away from a ball called Pluto, or a piece of paper with information about Pluto, including a picture or drawing, in a dark room and show how bright it would be during a Pluto day. Make sure the light is not in a lamp with a reflector, just a bare bulb free to send its light in all directions equally. Maybe a table lamp with the shade removed. That will not be dark like night. It will be brighter than a night on Earth under a full Moon, but clearly less than full noon sunlight. And feel the heat of that light at that distance. Hardly any. Compare that to the heat you feel 40 times closer to the bulb, about 2 or 3 inches from the bulb (don't actually touch the bulb, or you might get a burn!) That heat at 2 inches is what we feel from the Sun on Earth. Be sure to use a regular incandescent bulb and not an energy saving compact fluorescent bulb.

Answer 2

Reading 'invention' as 'science project,' I suggest getting styrofoam balls of appropriate size, painting them to suggest Pluto and its big moon Charon, connecting them with a stick, and hanging them from the stick's balance point so they rotate around each other as they do in their orbit about the sun:
  __.__
     |
     |
O---'-o

Answer 3

campbelp2002:

ABSOLUTELY COOL!

I wish I had thought of that myself.

:-)

Answer 4

??? please elaborate?