Naga fireballs (Thai: บั้งไฟพญานาค; RTGS: bang fai phaya nak), also known as bung fai phaya nak or "Mekong lights" and formerly "ghost lights",[1] are a phenomenon said to be seen annually on the Mekong River. Glowing balls are alleged to naturally rise from the water high into the air.[2] The balls are said to be reddish and to range in size 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.[3] The phenomenon is locally attributed to phaya nak, a giant serpent (Nāga) said to live in the Mekong.[1]
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