What's so special about the Blue Moon of January 31?

The event will occur again on December 31, 2028

The phrase ‘once in a blue moon’ symbolises rarity — and rightly so! An extraordinary celestial event is set to occur on January 31, 2018. On the day, sky gazers will witness the total lunar eclipse of a Supermoon.

What is a Supermoon?
A Supermoon occurs either on a new moon or full moon night when the moon is at its closest approach to Earth in its orbit. It is called a ‘Supermoon’ as the moon appears bigger and brighter in the sky.

What is a Blue Moon?
January 31 won’t just witness a Supermoon but also a Blue Moon. A Blue Moon is either the third full moon in a season of four full moons or the second full moon in a month. However, this does not mean that the moon will actually appear ‘blue’.

Why is Blue Moon called so?
The Blue Moon gets its name from an old American periodical ‘Farmers’ almanacs’ published in Maine, which began calling the third full moon in a season with four full moons a ‘Blue Moon.’ There are many theories why the term was used, but none of them provides any confirmation.

The final step in the evolution of the term ‘Blue Moon‘ took place in 1946 when an amateur astronomer James Hugh Pruett, wrote an article about the term ‘Blue Moon’ for Sky an Telescope magazine. By mistake, he simplified the definition found in Farmers’ Almanac and defined a Blue Moon as the second full moon in a month. Pruett’s error was discovered half a century later. But by that time, the definition had stuck.

What so special about January 31’s event?
January 31’s event will witness the total lunar eclipse of a Blue Moon. This last one occurred on March 31, 1866 — 152 years ago. This rare event will next take place on December 31, 2028, and then on January 31, 2037.

Happy star-gazing folks!