Tiandeng, also known as Kongming lantern or Chinese lantern, is a small hot-air balloon made of paper, with an opening at the bottom and a small fire hanging on it.

In Asia and the rest of the world, lanterns have traditionally been made for centuries for people to play with or as part of a long history of celebration. Sky lantern is the translation of Chinese name, but it is also called sky candle or fire balloon.

The overall design is a thin paper case, which may be between 30 cm and a few meters wide, with an opening at the bottom. The opening is usually about 10 to 30 cm wide (even the largest shell) and is surrounded by a hard collar, which is used to suspend the flame source and keep it away from the wall.

When lit, the flame heats the air inside the lantern, reducing its density and causing the lantern to rise into the air. Only when the flame continues to ignite, can the sky lamp fly in the air, and then the sky lamp sinks back to the ground.

When the flame is still on fire, the skylight may land, which may cause fire hazard. In a typical design, as long as the lantern stays upright, the paper won't get hot enough to ignite, but if the balloon tilts (for example, being hit by the wind or something), it may still be in the air and catch fire. Normally, all paper burns in seconds, but the source of the flame may stay on until it lands.

After the balloon lands, the remaining fine wire frame will rust very slowly, still posing a danger to animals that may be swallowed by it. In 2009, sky orbs Chinese lanterns, a British company, developed lanterns using biodegradable fire-resistant ropes instead of wires. Many other European manufacturers have adopted similar designs. In 2012, the same company released a patented design with a fire base after reporting a fire caused by a lantern.

It is also said that the sky lights pose a danger to the aircraft.

On July 1, 2013, the skylight ignited the "largest ever fire" in West Midlands, England, involving 100000 tons of recycled materials and causing about 6 million pounds of damage, landing at a plastic recycling plant in Smithwick. Images of lanterns lighting the fire were taken on CCTV. In response to the fire, Portland decided to stop selling skylights and recalled all its inventory on July 6, 2013.

In 2018, a pavilion in Rio de Janeiro convention center near the center of Rio de Janeiro, Brazil, was completely burned after a balloon was placed on the roof.