The Naga fireballs (Thai: บั้งไฟพญานาค; RTGS: bang fai phaya nak), also known as the Mekong lights, and “bung fai paya nak” by the locals, is a phenomenon with unconfirmed source said to be often seen in Thailand’s Mekong river, which is also seen in (Nong Khai province in Isan) and in Laos (Vientiane Province)—in which glowing balls are alleged to naturally rise from the water high into the air. The balls are said to be reddish and to have diverse sizes from smaller sparkles up to the size of basketballs; they quickly rise up to a couple of hundred metres before disappearing. The number of fireballs reported varies between tens and thousands per night. 
Naga fireballs have been reported over an approximately 250 kilometre long section of Mekong river with the center of this section approximately at Phon Phisai town in Amphoe Phon Phisai. Balls have also been reported rising from smaller rivers, lakes and ponds in this region.
Causes and beliefs
In contrast to the legend and lack of objective analysis of the Naga fireballs, a similar phenomenon in plasma physics is a free-floating plasma orb, which is created when surface electricity (e.g. from a capacitor) is discharged into a solution. Skeptic Brian Dunning writes that whatever is sailing through the air has mass, and "must have been physically propelled". It would be impossible for anyone across the half-mile river to hear a gunshot because it would take 2.5 seconds for the sound to travel to the spectators, and by then the crowd watching has already noticed the light, drowning out the sound when it would reach them. There is no science that can explain "the Naga Fireballs to be naturally produced burning gas bubbles."
A programme on Thai television in 2002 demonstrated that the fireballs were produced by tracer fire from soldiers on the Lao side of the river. This provoked furious protests and demonstrations from local villagers, who believe that the balls are produced by a mythical snake, the Naga or Phaya Naga, living in the river. The phenomenon has become more prominent since the furor over the TV programme, as well as the 2002 film by director Jira Maligool, Mekhong Full Moon Party.
Another explanation of the phenomenon is that the fireball is a result of flammable phosphine gas generated by the marshy environment.
- "5 natural events that science can't explain: The Naga fireballs". Mother Nature News.
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- Duangmee, Phoowadon (October 10, 2008), Let there be lights, The Nation, retrieved Dec 11, 2008
- Duangmee, Phoowadon (September 21, 2011). "Let there be lights". The Nation.
- "Free Floating Plasma Orb". American Physical Society.
- Brian Dunning (2009-12-09). "The Naga Fireballs: What is the source of the glowing balls that rise from the Mekong river each October?". Skeptoid: Critical Analysis of Pop Phenomena. Retrieved 2011-11-14.
- Gilliam, Ronald (16 June 2012). "eview: Mekhong Full Moon Party". Center of Southeast Asian Studies, University of Hawaii at Manoa. Retrieved 18 August 2012.
- "'Science Ministry solves Naga fireballs mystery'".