Vesak is a holiday which was traditionally celebrated by Buddhists and some Hindus on different days and in many different countries such as India, Nepal, Tibet, Thailand, Vietnam, China, Japan and others. This festival represents the birth, enlightenment, and death of Gautama Buddha in the southern tradition.
This holiday is also known as the Buddha day and people celebrate it every year on the full moon of the ancient lunar month which actually happens in May or early June. As it was previously mentioned, people celebrate the birth of Siddhattha Gotama or Buddha-to-be, his enlightenment at 35, when he becomes Buddha and then his final passing into the stage of Nirvana at the age of 80.
People believe that all these three events happened on full moon. In Buddhism, the death is not the end. Buddhism teaches about rebirth different from reincarnation. For those that are unenlightened and their minds are still full of desire, there is another life after death. But for the ones that have been freed from all the desires and are enlightened, there is no more rebirth. They do not die but pass into Nirvana or Nibbana.
There are some cultural or local differences to how people celebrate Vesak, but generally speaking the devoted Buddhists usually go to their nearer temple that day, while others stay there as long as the full moon lasts. The festival usually involves bringing and giving food as well as supplies and offerings for the temple.
One very interesting phenomenon happened just recently at the celebration of the Vesak festival and is definitely connected to the celebration of the birth and the expression of delight. It is the rainbow ring around the sun representing “clear light”. It leaves no sense of “leaving behind” but of moving along.
The rainbow has deep origins into Buddhism. It takes different forms such as the single rainbow, the double-reversed rainbow, and then the circular rainbow known as the “glory”. The rainbows in Tibetan art arise from sacred object and places and expand and intertwine with other rainbows. They originate from one point but dissolve somewhere into space. This phenomenon, the circular rainbow around the sun is believed to be an omen of the birth or death of a great teacher.