1.   Because they are the simplest kind of fire, flame balls are an ideal subject for researchers trying to fine-tune combustion models.

2.   But for two weeks last July, astronauts aboard the space shuttle Columbia observed how tiny floating flame balls burned in sealed, gas-filled chambers.

3.   The flame balls shrink as they use up the fuel and then wink out, which can take more than eight minutes.

4.   The surprises include blue flame balls, apparently akin to glowing spheres of ball lightning.