The Naga fireballs

Tracer rounds, marsh gas or plasma, and after twenty years nobody can say

Every October, on the full moon of the 11th lunar month that ends the Buddhist Lent, crowds of tens of thousands pack the Thai bank of the Mekong in Nong Khai province to watch glowing balls rise out of the river. They are called bang fai phaya nak, the fireballs of the Naga king, and by local belief they come from the Phaya Nak, the giant serpent said to live in the Mekong, welcoming the Buddha back to Earth. The centre of it all is Phon Phisai district, though sightings run along some 250 km of the river and are reported from smaller rivers, lakes and ponds too.

Accounts differ on what they look like. Thailand's folk-culture site describes them as smokeless, smell-less and soundless, thumb- to egg-sized, rising 20 to 30 metres straight up and vanishing without falling back; other reports speak of reddish balls from sparks to the size of a basketball climbing a couple of hundred metres, tens to thousands in a night. Until the mid-1980s locals called them ghost lights, and the name phaya nak lights is only a few decades old. A photograph sold all over Nong Khai claims to show American soldiers holding a seven-metre Naga caught in the Mekong in 1973, and a temple in Nong Khai city displays what it says are a Naga's fossil tooth and egg.

The festival has grown with the fame. In 2001 about 150,000 people came; after a 2002 film, Mekong Full Moon Party, and a television exposé the same year, attendance reportedly rose to 400,000, and Phon Phisai built concrete grandstands along the riverfront in 2003. The exposé, by the iTV programme Code Cracking, filmed Lao soldiers on the far bank firing tracer rounds into the sky, and the crowd cheering each one. It was widely taken as an attack on a sacred belief.

Explanations have not settled it. A Nong Khai pediatrician, Dr. Manos Kanoksilp, made marsh gas his life's study, but the skeptic Brian Dunning points out that such gas ignites with a bluish-green pop, never rises red like a rocket, and could not stay lit at those speeds. In 2021 Thais flying drones over the river posted pictures of people on the Lao bank shooting flares, and the Chulalongkorn biologist Jessada Denduangboripant said wide-angle photos made it obvious. That same year, during a COVID curfew, Lao authorities said it was extremely unlikely anyone could have fired flares without their knowledge, and believers cite elders who say they have seen the fireballs for decades, though no reliable record of them seems to predate the mid-20th century.