Today is 'Blue moon' day, celestial phenomena

Chennai, Jun 30 (UNI) People in India and some other parts of the world, including Australia, will witness a celestial phenomenon 'blue moon', or two full moons occurring in a single month.

The last full moon was on June 1.

''Blue moon' is an astronomical term used to describe the second full moon in a month, an event which occurs only once every two-and-a-half years,'' Tamil Nadu Science and Technology Centre Executive Director P Iyam Perumal told UNI here.

A full moon occurs every 29.5 days, while the length of an average month is roughly 30.5 days. This makes it very unlikely that any given month will have two full moons,'' he said.

However, the 'blue moon' does not mean that moon will be of blue colour, he said.

More traditionally, it was referred to as the fourth full moon in a season. That is, each of the four seasons of the year has three months, and will usually have three full moons, he added.

Each of the 12 full moons in a year has a unique name like 'Harvest Moon' and 'Hunter's Moon', he said.

But when a year has 13 moons, there is no name for this occasional moon and it was hence termed 'Blue Moon', Mr Perumal informed.

UNI