whats the name for this type of motor or engine

[werowance]

I am looking for what you would call this type of motor (assuming its a motor and not an engine)

heres a description of it, they are usually in a glass globe that kind of looks like a light bulb, there are 4 fins with one side white and one side black, they rotate on a tiny spindle when exposed to sunlight. its like one side of the fin is hot and the other is cold. it spins round and round when you put it in sun light. but its not electric I don't believe, just the heat differences on the fins.

what are these things called? we used to have one in grade school science class. I loved whatching that thing when I was a kid.

would you call that an engine or a motor?

 

[werowance]

google search for solar desk toys got me this one. but still doesn't tell me what they are called.

 

[mu38&Bg#]

Radiometer

 

[MachineTom]

The fins are in a vacuum, photons of light are reflected off the white surface, absorbed by the black, that small difference in energy causes the rotation.

 

[Cogsy]

It's called a Crookes Radiometer and it is a type of heat engine driven by ambient electromagnetic radiation in a partial vacuum (it won't work in high/full vacuum as it needs gas molecules to operate). They are very interesting items but I doubt many would have the equipment or skill to make one successfully at home. There are cheapies showing up on eBay around $20...

 

[werowance]

yep, after you all gave me the name I did more research, and looks like several have tried few have succeeded in making one at home due to the vacume issue. but for 20 bucks, I think ill ebay for one just for a desk toy.