\\\"Often, when the Moon is hanging low, it looks red for the same reason that sunsets are red, NASA explains. \\\"The atmosphere is full of aerosols much smaller than the ones injected by volcanoes. These aerosols scatter blue light, while leaving the red behind.\\\"
The term has traditionally, in the Maine Farmer's Almanac, referred to an \"extra\" full moon, where a year which usually has 12 full moons has 13 instead. The \"blue moon\" reference is applied to the third full moon in a season with four full moons, thus correcting the timing of the last month of a season that would have otherwise been expected too early. This happens every two to three years (seven times in the Metonic cycle of 19 years). The author of a March 1946 article in Sky & Telescope attempted to decipher the traditional practice of the editors of the Maine Farmers' Almanac by examining old issues of the almanac. Without enough almanacs to see the correct pattern, he conjectured the wrong rule for 'blue moons', which led to the modern colloquial misunderstanding that a blue moon is a second full moon in a single solar calendar month, with no link to the order it occurs in a season. The phrase \"once in a blue moon\" is also used idiomatically, which means once after a long time. An example in a sentence: \"My sister lives in Alaska, so I only see her once in a blue moon.\"
One lunation (an average lunar cycle) is 29.53 days. There are about 365.24 days in a tropical year. Therefore, about 12.37 lunations (365.24 days divided by 29.53 days) occur in a tropical year. In the widely used Gregorian calendar, there are 12 months (the word month is derived from moon) in a year, and normally there is one full moon each month, with the date of the full moon falling back by nearly one day every calendar month. Each calendar year contains roughly 11 days more than the number of days in 12 lunar cycles. The extra days accumulate, so every two or three years (seven times in the 19 year Metonic cycle), there is an extra full moon in the year. The extra full moon necessarily falls in one of the four seasons, giving that season four full moons instead of the usual three, and, hence, a \"blue\" moon.
The earliest recorded English usage of the term blue moon is found in an anti-clerical pamphlet (attacking the Roman clergy, and Cardinal Thomas Wolsey in particular) by two converted Greenwich friars, William Roy and Jerome Barlow, published in 1528 under the title Rede me and be not wrothe, for I say no thynge but trothe.The relevant passage reads:
It is not clear from the context that this refers to intercalation; the context of the passage is a dialogue between two priest's servants, spoken by the character \"Jeffrey\" (a brefe dialoge betwene two preste's servauntis, named Watkyn and Ieffraye). The intention may simply be that Jeffrey makes an absurd statement, \"the moon is blue\", to make the point that priests require laymen to believe in statements even if they are patently false.
In 2007, Joe Rao, Skywatching Columnist at Space.com, stated that many years previously he had speculated in Natural History magazine that the \"Blue Moon Rule\" might derive from belewe, which he described as an Old English word meaning 'to betray', because the extra full moon \"betrays the usual perception of one full moon per month.\" He then added that his speculation had been \"innovative\", but \"completely wrong\". In 2009, a less detailed version of this speculation was mentioned in Farmers' Almanac.
In the 19th and early 20th centuries, the Maine Farmers' Almanac listed blue moon dates for farmers. These correspond to the third full moon in a quarter of the year when there were four full moons (normally a quarter year has three full moons). Full moon names were given to each lunation in a season. The seasons used were those of the mean tropical year, equal in length, as opposed to the astronomical seasons which vary in length because the earth's speed in its orbit round the sun is not uniform.
To compare, in 1983 the equal seasons began at 1.48 AM on 23 March, 9.15 AM on 22 June, 4.42 PM on 21 September and 12.10 AM on 22 December, while the astronomical seasons began at 4.39 AM on 21 March, 11.09 PM on 21 June, 2.42 PM on 23 September and 10.30 AM on 22 December (all times GMT). When a season has four full moons the third is called the \"blue moon\" so that the last can continue to be called with the proper name for that season.
The most literal meaning of blue moon is when the moon (not necessarily a full moon) appears to a casual observer to be unusually bluish, which is a rare event. The effect can be caused by smoke or dust particles in the atmosphere, as has happened after forest fires in Sweden and Canada in 1950 and 1951, and after the eruption of Krakatoa in 1883, which caused the moon to appear blue for nearly two years. Other less potent volcanoes have also turned the moon blue. People saw blue moons in 1983 after the eruption of the El Chichón volcano in Mexico, and there are reports of blue moons caused by Mount St. Helens in 1980 and Mount Pinatubo in 1991. In the Antarctic diary of Robert Falcon Scott for July 11, 1911 his entry says, \"... the air thick with snow, and the moon a vague blue\".
Using the Maine Farmers' Almanac definition of blue moon (meaning the third full moon in a season of four full moons, but referenced to astronomical rather than equal seasons), blue moons have occurred on:
Two full moons in one month (the second of which is a \"blue moon\"):A blue moon can occur in January and the following March if there is no full moon at all in February, as is the case in the years 1999, 2018, and 2037.
This year, 2018, we have two months (January and March) with Blue Moons. They are Blue Moons by the monthly definition of the term: the second of two full moons to fall within a single calendar month. The first Blue Moon comes on January 31, 2018, and the second on March 31, 2018. Meanwhile, the month of February 2018 has no full moon at all.
The precise instant of the January 31 Blue Moon is 13:27 UTC. Although the full moon happens at the same instant worldwide, the hour differs by time zone. At North American and U.S. times zones, that places the time of January 31 Blue Moon at:
Read our wrap story here about the meet-up of a Blue Moon, supermoon and total lunar eclipse. See more reader photos here! It was the first total lunar eclipse since 2015 and the first Blue Moon Blood Moon visible from the U.S. since 1866! See our video highlight reel above and read for more amazing photos, and details on what made the event so special.
The second full moon and the lunar eclipse will occur on the night of Jan. 31 or the morning of Feb. 1. And the supermoon will take place on the night of Jan. 30, which is technically one day before the moon reaches peak fullness, but even NASA is willing to call the event a supermoon nonetheless. [How to Photograph the Supermoon: NASA Pro Shares His Tips]
On Jan. 31, not every place on Earth will see the Blue Moon this month, because the second full moon of January won't technically appear in those places until Feb. 1. These places include regions in eastern Asia and eastern Australia, where skywatchers won't see the first full moon until Jan. 2 and the next full moon until the morning of Feb. 1. For example, in Melbourne, Australia, the full moon arrives on Jan. 2 at 1:24 p.m. local time, and the next full moon is on Feb. 1 at 1:26 a.m., so skywatchers will technically miss the Blue Moon by less than 2 hours.
But their fellow Aussies in Perth, in the southwestern part of the country, will get one, since the first full moon occurs on Jan. 2 at 10:24 a.m. local time, so the moon will still look quite full when it rises at 7:35 p.m. On Jan. 31, the moon rises at 7:09 p.m. and reaches fullness at 9:26 p.m.
The real star of the show for moon watchers is the lunar eclipse on Jan. 31. The supermoon (when the moon reaches its closest point to Earth in this orbit) will be the day before, on Jan. 30 at 4:58 a.m. EST (0958 GMT). The moon will be 223,068 miles (358,994 kilometers) from Earth, compared to the average distance of 238,855 miles (384,400 km), according to NASA.
Though a supermoon does appear slightly larger in the sky than a full moon that takes place when Earth's lunar companion is farther away from us in its orbit, the difference is nearly impossible for most skywatchers to notice because the moon is so bright and the maximum possible difference in the moon's apparent size is small (only about 14 percent), according to NASA.
Unlike solar eclipses, which are only visible from specific places on Earth, lunar eclipses are visible from anywhere it is nighttime. Lunar eclipses don't occur every month because the plane of the lunar orbit is slightly tilted relative to the plane of the Earth's orbit, so the Earth, sun and moon don't always line up to put the moon in Earth's shadow. For the Jan. 31 lunar eclipse, viewers in some places will not be able to see the entire event because it starts near moonrise or moonset. Lunar eclipses are only visible on Earth's night side.
Observers in New York City will see the moon enter Earth's penumbra (the lighter, outer part of its shadow) at 5:51 a.m. on Jan. 31. The penumbra darkens the moon only a little; unless you're especially keen eyed, it is often difficult to notice. The moon will touch the umbra, the darker part of the shadow that gives the eclipse the distinctive look of darkening and reddening the moon, at 6:48 a.m. local time. But the moon sets only 16 minutes later, so New Yorkers will get to see only the first part of the eclipse. To see as much of the eclipse as possible, you'll want to be near a flat western horizon. 59ce067264