C.C.
The fire in the sky lantern heats up the air in it, and lowers the density of the lantern... that's why it floats. It will come down only when the flame goes out. There ARE possible fire hazards, but it's only a minor possibility, and the lanterns are fire retardant. DH has a Chinese friend who lets his kids play with paper lanterns during Chinese festivals. There's never been a fire hazard as long as I can recall.