Movie Blue Moon
Alysa Guillama
Only under certain atmospheric conditions. In the aftermath of the massive 1884 volcanic eruption of Krakatoa, a tremendous cloud of ash and dust was injected into the stratosphere (5 to 30 miles above the Earth's surface); this aerosol cloud caused both the moon and sun appear blue from many locations in the Northern Hemisphere for many months after the explosion.
And on September 24th, 1950, a 200-mile-wide swath of smoke from a series of smoldering fires in the forests of Northern Alberta in Canada cast an awesome pall over the Great Lakes, parts of New York State and Southern New England. The smoke produced an unusual midday darkness and caused the disk of the sun to shine in eerie hues of pink, blue and even purple!
To see the moon actually turn blue, requires either a massive volcanic eruption or a giant pall of airborne smoke (such as in 1950). But such events are few and far between . . . perhaps occurring only about half a dozen times per century. Calendrical blue moons are much more frequent, occurring (on average) about every 2.5 to nearly 3 years.
As the cycle of the phases of the moon lasts approximately one month, we typically experience 12 full moons each year. Many cultures have given distinct names to each month's full moon. 12 months, 12 full moons, 12 names. Simple right?
Well, not quite. Here's where the Blue Moon comes into the equation.
Blue Moons occur once every two to three years, according to NASA. As there are roughly 29.5 days between full moons, February will never experience a monthly Blue Moon as it only has 28 days in a common year and 29 in a leap year. Sometimes February doesn't have a Full Moon at all, this is known as a Black Moon, according to Time and Date.
According to NASA Science, other volcanic eruptions have also been known to cause blue moons including the 1983 eruption of El Chichon volcano in Mexico and the eruptions of Mt. St. Helens in 1980 and Mount Pinatubo in 1991.
Explore Blue Moons in a nutshell with ESA's useful Blue Moon infographic. Check out this cool image of a Blue Moon captured by the European weather satellite MSG-3 just before the moon disappeared out of sight. Discover the difference between types of full moons with NASA.
Daisy Dobrijevic joined Space.com in February 2022 having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K. Daisy is passionate about all things space, with a penchant for solar activity and space weather. She has a strong interest in astrotourism and loves nothing more than a good northern lights chase! "}), " -0-10/js/authorBio.js"); } else console.error('%c FTE ','background: #9306F9; color: #ffffff','no lazy slice hydration function available'); Daisy DobrijevicSocial Links NavigationReference EditorDaisy Dobrijevic joined Space.com in February 2022 having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K. Daisy is passionate about all things space, with a penchant for solar activity and space weather. She has a strong interest in astrotourism and loves nothing more than a good northern lights chase!
A blue moon refers either to the presence of a second full moon in a calendar month, to the third full moon in a season containing four, or to a moon that appears blue due to atmospheric effects.[1]
The Moon usually comes full twelve times in a year, three times in eachseason... However, occasionally the moon comes full thirteen times in a year.This was considered a very unfortunate circumstance, especially by themonks who had charge of the calendar. It became necessary for themto make a calendar of thirteen months, and it upset the regular arrangementof church festivals. For this reason thirteen came to be considered anunlucky number. Also, this extra moon had a way of coming in each ofthe seasons so that it could not be given a name appropriate to the timeof year like the other moons. It was usually called the Blue Moon... In olden times the almanacmakers had much difficulty calculating the occurrence of the Blue Moonand this uncertainty gave rise to the expression "Once in a Blue Moon".[3]
Despite the 187 blue moons appearing across the 200 years in this table, only 146 years have any of these 3 types of blue moons, leaving 54 years (thus averaging just over 1 year in every 4) which have none of the 3 rules represented in that calendar year.
While not totally unexpected (given the overlapping frequencies of these 3 rules), it so happens there are not any 2 sequential years (at least within these 200) wherein none of the 3 types of blue moon occur.
Conversely, despite the preponderance of years with blue moons (of at least 1 type) occurring in this 200-year range, there are no instances of more than 4 sequential years having a blue moon, of any of these 3 types -- i.e. at least 1 year out of every 5 sequential years has none of the 3 types appearing.
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. So the date of the full moon falls back by nearly one day every calendar month on average. Each calendar year contains roughly 11 days more than the number of days in 12 lunar cycles, 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 (however defined), giving that season four full moons instead of the usual three.[47][48][49]
Given that a year is approximately 365.2425 days and a synodic orbit is 29.5309 days,[50] then there are about 12.368 synodic months in a year. For this to add up to another full month would take 1/0.368 years. Thus it would take about 2.716 years, or 2 years, 8 months, and 18 days for another Pruett blue moon to occur. Or approximately once in 32.5 months on an average.
You might find particles of this size in the air above you when, for example, a wildfire is raging nearby. Particles of this size are very efficient at scattering red light. When these particles are present in our air, and the moon shines through them, the moon may appear blue in color.
The time between one full moon and the next is close to the length of a calendar month. So the only time one month can have two full moons is when the first full moon happens in the first few days of the month. This happens every two to three years, so this sort of Blue Moon comes about that often.
Had James Hugh Pruett looked at the actual date of the 1937 Blue Moon, he would have found that it had occurred August 21, 1937. Also, there were only 12 full moons in 1937. You generally need 13 full moons in one calendar year to have two full moons in one calendar month.
People sometimes refer to two types of blue moons: monthly and seasonal. This upcoming moon is a monthly blue moon. Seasonal blue moons occur when there are four full moons in a single season (spring, summer, fall and winter) instead of the usual three.
For example the 'Wolf Moon' is usually the full Moon occurring within January. With the cycle of the phases of the Moon lasting approximately one month, and there being 12 months in a year, we typically have 12 full moons each year.
Which of the 13 full moons is the blue moon is up for debate. Traditionally the definition of a blue moon is the third full Moon in an astronomical season containing four full moons. This is the most complicated definition for people using the standard calendar, as the astronomical seasons begin and end at the equinoxes and solstices (e.g. the winter season begins at the winter solstice and ends at the spring equinox, the spring season begins at the spring equinox and ends at the summer solstice and so on).
Another definition of the blue moon, perhaps the more commonly used due to its simplicity, actually started as a mistake, made in the 1940s and perpetuated by radio shows and the Trivial Pursuit board game through the 1980s.
This definition describes the blue moon as the second full Moon in any calendar month with two full moons. As February 2018 had no full moon in it, both January and March ended up with two full moons, so by this definition both months contained blue moons.
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