The Vixakha Bouxa festival (also written Visakha Bouça) commemorates the birth, enlightenment, and death of the Buddha, which are all said to have happened on the same date. It is held around the month of May or Vesak, based on the lunar calendar (celebration on the 15th day of the waxing moon of the 6th month).
One part of the Vixakha Bouxa festival is called Boun Bang Fay, or Rocket Festival. As this is during the hottest and driest season of the year, large homemade rockets are launched into the sky in an attempt to convince the celestial beings to send down rain. This rockets are made with 6 to 24kg of gunpowder, and can reach several hundred meters. Villages and villagers are competiting each other, the chief head of the village "responsible" for the defeat in case of the rocket doesn’t work well...