Full moon day happens to be the lunar phase while moon comes in between sun and earth.
During Full moon day period, when viewed from the Earth, the Moon’s hemisphere which is visible from the earth is fully lightened by the Sun. Thus, it looks round. During Full moon day time, moon’s hemisphere which is not seen by earth remains totally dark. The Moon orbits the Earth about once a month from about 1 light second away. It approximately takes 27 days for completing the orbit. The Moon's diameter is about 1/4 that of the Earth, and from the Earth's surface appears to have almost exactly the same angular size as the Sun. around the Earth. Since the month of February which is also called lunar month contains only 29 days excepting leap year, thus, the dates of full Moon changes every year. The Light of the Moon that reflects from the Sun is said to be the brightest on this night.
Full Moon dates back to the United States, which was then called Native America where tribes kept a track of every season by naming it differently. This method was then adopted by England where a little change were made and then followed by the Europeans. It became tradition from the past that assigning different names for each and every full moon during the entire year. Although determination of significant names for each full moon has taken different shapes from time to time and place to place. An ancient system of choosing names was the resultant criteria of different seasons and even quarters of each year. For instance, the Full Moon just before Easter was named as the Egg Moon. This would be the first moon and it will be visible up above the sky after 21st March. The Lenten Moon happened to be the last visible moon of the year. Full moon day appears on or before March 21st. But trend has changed and modern world earmarks each full moon by the chosen name from the Gregorian calendar. Though, this allocation method of naming of full moon often effectuates the similarity of modern name with traditional one. In fact, the name Monday originates from Moon-day.
Many religions have their New Year starting from the Full Moon Day of a particular month like in Theravada countries, Thailand, Burma, Sri Lanka, Cambodia and Lao, the New Year is celebrated for three days from the first full moon day in April. In Mahayana countries the New Year starts on the first full moon day in January. But the Buddhist New Year depends on the country of origin or ethnic background of the people taking the example of Chinese, Koreans and Vietnamese celebrate late January or early February according to the lunar calendar, like wise Tibetans usually celebrate about one month later. So, it depends from people to people and their religious customs and belief when they want to celebrate it.
As per human beliefs it is also said that Full Moon day is the best time to start of a new venture/business etc. Because it drives away all the evils and misfortunes. In Hindu religion it holds a lot of significance.According to it, a full moon day is called either “Purnima” or “Puranmasi.’ A special ritual is organized on this day at temples. Religious rites of purifications are held with symbolic offerings, symbolizing spiritual purification, where thousands of Hindus as well as non Hindus participate. However, in today’s era different people have different beliefs and customs which keep on changing from time to time what has not changed from the past and will definitely not change in the Future is the Moon.