![Eclipse vs new or full moons, annotated](https://upload.wikimedia.org/wikipedia/commons/b/b9/Eclipse_vs_new_or_full_moons%2C_annotated.svg)
The full moon is the
lunar phase
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
when the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
appears fully illuminated from
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's perspective. This occurs when Earth is located between the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
and the Moon (when the
ecliptic longitudes of the Sun and Moon
differ by 180°). This means that the lunar hemisphere facing Earth—the
near side
The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a ...
—is completely sunlit and appears as an approximately circular disk. The full moon occurs roughly once a
month.
The time interval between a full moon and the next repetition of the same phase, a
synodic month
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.
Variations
In Shona, Middle Eastern, and Europ ...
, averages about 29.53 days. Therefore, in those
lunar calendar
A lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most commonly used calendar, the Gre ...
s in which each month begins on the day of the
new moon
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse.
...
, the full moon falls on either the 14th or 15th day of the
lunar month
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.
Variations
In Shona, Middle Eastern, and Europ ...
. Because a calendar month consists of a
whole number of days, a month in a lunar calendar may be either 29 or 30 days long.
Characteristics
A full moon is often thought of as an event of a full night's duration, although
its phase seen from Earth continuously waxes or wanes, and is full only at the instant when waxing ends and waning begins. For any given location, about half of these maximum full moons may be visible, while the other half occurs during the day, when the full moon is below the horizon. As the Moon’s orbit is inclined by 5.145° from the ecliptic, it is not generally perfectly opposite from the Sun during full phase, therefore a full moon is in general not perfectly full except on nights with a
lunar eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth ...
as the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
crosses the ecliptic at opposition from the Sun.
Many
almanac
An almanac (also spelled ''almanack'' and ''almanach'') is an annual publication listing a set of current information about one or multiple subjects. It includes information like weather forecasts, farmers' planting dates, tide tables, and other ...
s list full moons not only by date, but also by their exact time, usually in
Coordinated Universal Time
Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used ...
(UTC). Typical monthly
calendar
A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a physi ...
s that include lunar phases may be offset by one day when prepared for a different
time zone
A time zone is an area which observes a uniform standard time for legal, Commerce, commercial and social purposes. Time zones tend to follow the boundaries between Country, countries and their Administrative division, subdivisions instead of ...
.
The full moon is generally a suboptimal time for
astronomical observation
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical m ...
of the Moon because shadows vanish. It is a poor time for other observations because the bright
sunlight reflected by the Moon, amplified by the
opposition surge
The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer. The term is most wid ...
, then
outshines many stars.
Formula
The date and approximate time of a specific full moon (assuming a circular orbit) can be calculated from the following equation:
:
where ''d'' is the number of days since 1 January 2000 00:00:00 in the
Terrestrial Time
Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth.
For example, the Astronomical Almanac uses T ...
scale used in astronomical
ephemerides
In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly vel ...
; for
Universal Time
Universal Time (UT or UT1) is a time standard based on Earth's rotation. While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with ...
(UT) add the following approximate correction to ''d'':
:
days
where ''N'' is the number of full moons since the first full moon of 2000. The true time of a full moon may differ from this approximation by up to about 14.5 hours as a result of the non-circularity of the Moon's orbit. See
New moon
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse.
...
for an explanation of the formula and its parameters.
The age and apparent size of the full moon vary in a cycle of just under 14
synodic month
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.
Variations
In Shona, Middle Eastern, and Europ ...
s, which has been referred to as a
full moon cycle
A supermoon is a full moon or a new moon that nearly coincides with perigee—the closest that the Moon comes to the Earth in its elliptic orbit—resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. ...
.
Lunar eclipses
When the Moon moves into
Earth's shadow
Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes ...
, a
lunar eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth ...
occurs, during which all or part of the Moon's face may appear reddish due to the
Rayleigh scattering
Rayleigh scattering ( ), named after the 19th-century British physicist Lord Rayleigh (John William Strutt), is the predominantly elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the ...
of blue wavelengths and the
refraction
In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomeno ...
of
sunlight
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...
through
Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
. Lunar eclipses happen only during a full moon and around points on
its orbit where the
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...
may pass through the planet's shadow. A lunar eclipse does not occur every month because the Moon's orbit is
inclined
Incline, inclined, inclining, or inclination may refer to:
*Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.)
*Slope, the tilt, steepn ...
5.145° with respect to the
ecliptic
The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...
plane of Earth; thus, the Moon usually passes north or south of Earth's shadow, which is mostly restricted to this
plane of reference
In celestial mechanics, the plane of reference (or reference plane) is the plane used to define orbital elements (positions). The two main orbital elements that are measured with respect to the plane of reference are the inclination and the longi ...
. Lunar eclipses happen only when the full moon occurs around either
node of its orbit (ascending or descending). Therefore, a lunar eclipse occurs about every six months, and often two weeks before or after a
solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six month ...
, which occurs during a
new moon
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse.
...
around the opposite node.
In folklore and tradition
![Moon and red blue haze](https://upload.wikimedia.org/wikipedia/commons/0/06/Moon_and_red_blue_haze.jpg)
Full moons are traditionally associated with
insomnia
Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...
(inability to sleep),
insanity
Insanity, madness, lunacy, and craziness are behaviors performed by certain abnormal mental or behavioral patterns. Insanity can be manifest as violations of societal norms, including a person or persons becoming a danger to themselves or to ...
(hence the terms ''lunacy'' and ''lunatic'') and various "magical phenomena" such as
lycanthropy
In folklore, a werewolf (), or occasionally lycanthrope (; ; uk, Вовкулака, Vovkulaka), is an individual that can shapeshift into a wolf (or, especially in modern film, a therianthropic hybrid wolf-like creature), either purposely or ...
. Psychologists, however, have found that there is no strong evidence for effects on human behavior around the time of a full moon. They find that studies are generally not consistent, with some showing a positive effect and others showing a negative effect. In one instance, the 23 December 2000 issue of the ''
British Medical Journal
''The BMJ'' is a weekly peer-reviewed medical trade journal, published by the trade union the British Medical Association (BMA). ''The BMJ'' has editorial freedom from the BMA. It is one of the world's oldest general medical journals. Origi ...
'' published two studies on dog bite admission to hospitals in
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
and
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. The study of the
Bradford Royal Infirmary
Bradford Royal Infirmary is a large teaching hospital in Bradford, West Yorkshire, England, and is operated by the Bradford Teaching Hospitals NHS Foundation Trust. The infirmary is affiliated with the Leeds School of Medicine.
History
The ho ...
found that dog bites were twice as common during a full moon, whereas the study conducted by the public hospitals in Australia found that they were less likely.
![Triple-Goddess-Waxing-Full-Waning-Symbol](https://upload.wikimedia.org/wikipedia/commons/c/cb/Triple-Goddess-Waxing-Full-Waning-Symbol.svg)
The symbol of the
Triple Goddess
A triple deity is a deity with three apparent forms that function as a singular whole. Such deities may sometimes be referred to as threefold, tripled, triplicate, tripartite, triune, triadic, or as a trinity. The number three has a long history ...
is drawn with the circular image of the full moon in the center flanked by a left facing crescent and right facing crescent, representing a maiden, mother and crone archetype.
Full moon names
Historically, month names are names of moons (
lunation
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.
Variations
In Shona, Middle Eastern, and Europ ...
s, not necessarily full moons) in
lunisolar calendar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the Ea ...
s. Since the introduction of the solar
Julian calendar
The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandr ...
in the Roman Empire, and later the
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years dif ...
worldwide, people no longer perceive month names as "moon" names. The traditional
Old English month names were equated with the names of the Julian calendar from an early time (soon after
Christianization
Christianization ( or Christianisation) is to make Christian; to imbue with Christian principles; to become Christian. It can apply to the conversion of an individual, a practice, a place or a whole society. It began in the Roman Empire, conti ...
, according to the testimony of
Bede
Bede ( ; ang, Bǣda , ; 672/326 May 735), also known as Saint Bede, The Venerable Bede, and Bede the Venerable ( la, Beda Venerabilis), was an English monk at the monastery of St Peter and its companion monastery of St Paul in the Kingdom o ...
around AD 700).
Some full moons have developed new names in modern times, such as "
blue moon
A blue moon is an additional full moon that appears in a subdivision of a year: the third of four full moons in a season.
The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon a ...
", as well as "harvest moon" and "hunter's moon" for the full moons of autumn.
Lunar eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth ...
s occur only at a full moon and often cause a reddish hue on the
near side of the Moon
The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a ...
. This full moon has been called a blood moon in popular culture.
Harvest and hunter's moons
![harvest moon](https://upload.wikimedia.org/wikipedia/commons/7/78/Harvest_moon.jpg)
The "harvest moon" and the "hunter's moon" are traditional names for the full moons in late
summer
Summer is the hottest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, the earliest sunrise and latest sunset occurs, daylight hours are longest and dark hours are shortest, wit ...
and in the
autumn
Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September ( Northern Hemisphere) or March ( Sou ...
in the
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, usually in September and October, respectively. It is celebrated by festivities such as the Chinese
Mid-Autumn Festival
The Mid-Autumn Festival (Chinese: / ), also known as the Moon Festival or Mooncake Festival, is a traditional festival celebrated in Chinese culture. Similar holidays are celebrated in Japan (), Korea (), Vietnam (), and other countries in Eas ...
, which is as important as the
Chinese New Year
Chinese New Year is the festival that celebrates the beginning of a New Year, new year on the traditional lunisolar calendar, lunisolar and solar Chinese calendar. In Sinophone, Chinese and other East Asian cultures, the festival is commonly r ...
.
The "harvest moon" (also known as the "barley moon" or "full corn moon") is the full moon nearest to the
autumnal equinox (22 or 23 September), occurring anytime within two weeks before or after that date. The "hunter's moon" is the full moon following it. The names are recorded from the early 18th century. The ''
Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
'' entry for "harvest moon" cites a 1706 reference, and for "hunter's moon" a 1710 edition of ''The British Apollo'', where the term is attributed to "the country people" ("The Country People call this the Hunters-Moon.") The names became traditional in
American folklore
American folklore encompasses the folklores that have evolved in the present-day United States since Europeans arrived in the 16th century. While it contains much in the way of Native American tradition, it is not wholly identical to the tribal ...
, where they are now often popularly attributed to
Native Americans. The
Feast of the Hunters' Moon
Feast of the Hunters’ Moon is a weekend festival and historical reenactment held on a weekend in October since 1968, at the present-day site of Fort Ouiatenon, a replica 18th century French military and trading post near West Lafayette, Indian ...
is a yearly festival in
West Lafayette, Indiana
West Lafayette () is a city in Wabash Township, Tippecanoe County, Indiana, United States, about northwest of the state capital of Indianapolis and southeast of Chicago. West Lafayette is directly across the Wabash River from its sister city, ...
, held in late September or early October each year since 1968. In 2010, the harvest moon occurred on the night of the equinox itself (some 5 hours after the moment of equinox) for the first time since 1991, after a period known as the
Metonic cycle
The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recu ...
.
All full moons rise around the time of
sunset
Sunset, also known as sundown, is the daily disappearance of the Sun below the horizon due to Earth's rotation. As viewed from everywhere on Earth (except the North and South poles), the equinox Sun sets due west at the moment of both the spring ...
. Since the moon moves eastward among the stars faster than the sun, lunar
culmination
In observational astronomy, culmination is the passage of a celestial object (such as the Sun, the Moon, a planet, a star, constellation or a deep-sky object) across the observer's local meridian. These events were also known as meridian transits ...
is delayed by about 50.47 minutes (on average) each day, thus causing moonrise to occur later each day.
Due to the high
lunar standstill
A lunar standstill or lunistice is when the moon reaches its furthest north or furthest south point during the course of a month (specifically a draconic month of about 27.2 days). The declination (a celestial coordinate measured as the angle f ...
, the harvest and hunter's moons of 2007 were special because the time difference between moonrises on successive evenings was much shorter than average. The moon rose about 30 minutes later from one night to the next, as seen from about 40° N or S latitude (because the full moon of September 2007 rose in the northeast rather than in the east). Hence, no long period of darkness occurred between sunset and moonrise for several days after the full moon, thus lengthening the time in the evening when there is enough
twilight
Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this il ...
and
moonlight
Moonlight consists of mostly sunlight (with little earthlight) reflected from the parts of the Moon's surface where the Sun's light strikes.
Illumination
The intensity of moonlight varies greatly depending on the lunar phase, but even the ful ...
to work to get the harvest in.
Farmers' Almanacs
The ''
Maine Farmers' Almanac
Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and nort ...
'' from around the 1930s began to publish Native American "Indian" full moon names, some of which had been adopted by
colonial Americans.
The ''
Farmers' Almanac
''Farmers' Almanac'' is an annual American periodical that has been in continuous publication since 1818. Published by Geiger of Lewiston, Maine, the ''Farmers' Almanac'' provides long-range weather predictions for both the U.S. and Canada. The ...
'' (since 1955 published in Maine, but not the same publication as the ''Maine Farmers' Almanac'') continues to do so.
An early list of "Indian month names" was published in 1918 by
Daniel Carter Beard
Daniel Carter "Uncle Dan" Beard (June 21, 1850 – June 11, 1941) was an American illustrator, author, youth leader, Georgist and social reformer who founded the Sons of Daniel Boone in 1905, which Beard later merged with the Boy Scouts of Ameri ...
in his ''The American Boy's Book of Signs, Signals and Symbols'' for use by the
boy scouts
Boy Scouts may refer to:
* Boy Scout, a participant in the Boy Scout Movement.
* Scouting, also known as the Boy Scout Movement.
* An organisation in the Scouting Movement, although many of these organizations also have female members. There are ...
.
Such names have gained currency in
American folklore
American folklore encompasses the folklores that have evolved in the present-day United States since Europeans arrived in the 16th century. While it contains much in the way of Native American tradition, it is not wholly identical to the tribal ...
. They appear in print more widely outside of the almanac tradition from the 1990s in popular publications about the Moon.
''Mysteries of the Moon'' by Patricia Haddock ("Great Mysteries Series", Greenhaven Press, 1992) gave an extensive list of such names along with the individual tribal groups they were supposedly associated with. Haddock supposes that certain "Colonial American" moon names were adopted from
Algonquian languages
The Algonquian languages ( or ; also Algonkian) are a subfamily of Indigenous languages of the Americas, indigenous American languages that include most languages in the Algic languages, Algic language family. The name of the Algonquian language f ...
(which were formerly spoken in the territory of New England), while others are based in European tradition (e.g. the Colonial American names for the May moon, "Milk Moon", "Mother's Moon", "Hare Moon" have no parallels in the supposed native names, while the name of November, "Beaver Moon" or “Sponge Moon” is supposedly based in an
Algonquian language).
The Long Night's Moon is the last full moon of the year and the one nearest the
winter solstice
The winter solstice, also called the hibernal solstice, occurs when either of Earth's poles reaches its maximum tilt away from the Sun. This happens twice yearly, once in each hemisphere ( Northern and Southern). For that hemisphere, the winte ...
.
"Ice Moon" is also used to refer to the first full moon of January or February.
Hindu full moon festivals
In Hinduism, most festivals are celebrated on auspicious days. Many of the Hindu festivals are celebrated on days with a full moon at night.
Different parts of India celebrate the same day with different names, as listed below:
#Chaitra Purnima – Gudi Padua, Yugadi,
Ugadi
Ugadi or Yugadi, also known as Samvatsarādi (), is New Year's Day according to the Hindu calendar and is celebrated in the states of Andhra Pradesh, Telangana, and Karnataka in India. It is festively observed in these regions on the first ...
, Hanuman Jayanti (15 April 2014)
#Vaishakh Purnima – Narasimh Jayanti,
Buddha Jayanthi (
Buddha's Birthday
Buddha's Birthday (also known as Buddha Jayanti, also known as his day of enlightenment – Buddha Purnima, Buddha Pournami) is a Buddhist festival that is celebrated in most of East Asia and South Asia commemorating the birth of the Gautama ...
) (14 May 2014)
#Jyeshtha Purnima – Vat Savitri Vrat
Vat Purnima
Vat Purnima (, , also called ''Vat Savitri'' Vrat) is a Hindu celebration observed by married women in Nepal, North India and in the Western Indian states of Maharashtra, Goa, Kumaon, Gujarat. On this Purnima (full moon) during the three days of t ...
(8 June 2014)
#Ashadh Purnima –
Guru Purnima
Guru Purnima (Poornima) is a tradition dedicated to all the spiritual and academic Gurus, who are evolved or enlightened humans, ready to share their wisdom, based on Karma Yoga. It is celebrated as a festival in India, Nepal and Bhutan by Hi ...
, Vyas Purnima (important day for starting education and honoring teachers
)
#Shravan Purnima – Good day for starting Upanayana day, Avani Avittam,
Raksha Bandhan
Raksha Bandhan Quote: m Hindi ''rakśābandhan'' held on the full moon of the month of Savan, when sisters tie a talisman (rakhi q.v.) on the arm of their brothers and receive small gifts of money from them. is a popular and traditionally Hin ...
. Conceptually
Onam
Onam ( ) is an annual Indian harvest festival celebrated predominantly by the Hindus of Kerala. A major annual event for Keralites, it is the official festival of the state and includes a spectrum of cultural events.
Onam commemorates Vamana ...
also comes on this day.
#Bhadrapad Purnima – Start of
Pitru Paksha
Pitru Paksha ( sa, पितृ पक्ष, ; lit. "fortnight of the paternal ancestors") is a 16–lunar day period in Hindu calendar when Hindus pay homage to their ancestors (Pitrs), especially through food offerings. The period is also k ...
,
Madhu Purnima
Modhu Purnima ( bn, মধু পূর্ণিমা, lit=honey full-moon) also known as Honey Full Moon Festival or Honey-offering Festival is a Buddhist festival celebrated in Bangladesh by the Barua and Chakma people of Chittagong and by th ...
#Ashvin Purnima –
Sharad Purnima
Sharad Purnima (also known as Kumara Purnima, Kojagari Purnima, Navanna Purnima, Kojagrat Purnima or Kaumudi Purnima) is a religious festival celebrated on the full moon day of the Hindu lunar month of Ashvin (September to October), marking t ...
#
Kartik Poornima
Kartika Purnima is a Hindu, Sikh and Jain cultural festival that is celebrated on Purnima (full moon day), the 15th (or 30th) lunar day of the month of Kartika. It falls in November or December of the Gregorian calendar
The Gregorian ...
–
Karthikai Deepam festival, Thrukkarthika (in Kerala)
#Margasirsha Purnima –
Thiruvathira
Thiruvathira or Thiruvathirai or Arudhra Darisanam is a Hindu festival celebrated in the Indian states of Kerala and Tamil Nadu. Thiruvathirai (Arudhra) in Tamil means "sacred big wave". In Chidambaram in Tamil Nadu, the Sri Natarajar temple ...
, Dathatreya Jayanthi
#Pushya Purnima –
Thaipusam
Thaipusam or Thaipoosam (Tamil: தைப்பூசம், ''taippūcam'' ?), is a festival celebrated by the Hindu Tamil community on the full moon in the Tamil month of ''Thai'' (January/February), usually coinciding with Pushya star, kno ...
, Shakambharee Purnima
#
Magha Purnima
Maghi Purnima, also known by the name of Magha Purnima, is known to be a day of the full moon that occurs during the Hindu calendar month of Magh. This day falls during the Gregorian calendar month of January or February. During this time period, ...
#Phalguna Purnima –
Holi
Holi (), also known as the Festival of Colours, the Festival of Spring, and the Festival of Love,The New Oxford Dictionary of English (1998) p. 874 "Holi /'həʊli:/ noun a Hindu spring festival ...". is an ancient Hindu religious festival ...
Lunar and lunisolar calendars
![Christmas full moons 1977-2091](https://upload.wikimedia.org/wikipedia/commons/c/c8/Christmas_full_moons_1977-2091.gif)
Most pre-modern calendars the world over were
lunisolar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the Ea ...
, combining the solar year with the lunation by means of
intercalary month
Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months.
So ...
s.
The Julian calendar abandoned this method in favour of a purely solar reckoning while conversely the 7th-century
Islamic calendar
The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or ...
opted for a purely lunar one.
A continuing lunisolar calendar is the
Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel. I ...
. Evidence of this is noted in the dates of
Passover
Passover, also called Pesach (; ), is a major Jewish holidays, Jewish holiday that celebrates the The Exodus, Biblical story of the Israelites escape from slavery in Ancient Egypt, Egypt, which occurs on the 15th day of the Hebrew calendar, He ...
and
Easter
Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samuel ...
in
Judaism
Judaism ( he, ''Yahăḏūṯ'') is an Abrahamic, monotheistic, and ethnic religion comprising the collective religious, cultural, and legal tradition and civilization of the Jewish people. It has its roots as an organized religion in the ...
and
Christianity
Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global pop ...
, respectively. Passover falls on the full moon on 15 Nisan of the Hebrew calendar. The date of the Jewish
Rosh Hashana
Rosh HaShanah ( he, רֹאשׁ הַשָּׁנָה, , literally "head of the year") is the Jewish New Year. The biblical name for this holiday is Yom Teruah (, , lit. "day of shouting/blasting") It is the first of the Jewish High Holy Days (, , " ...
and
Sukkot
or ("Booths, Tabernacles")
, observedby = Jews, Samaritans, a few Protestant denominations, Messianic Jews, Semitic Neopagans
, type = Jewish, Samaritan
, begins = 15th day of Tishrei
, ends = 21st day of Tishre ...
festivals along with all other
Jewish holidays
Jewish holidays, also known as Jewish festivals or ''Yamim Tovim'' ( he, ימים טובים, , Good Days, or singular , in transliterated Hebrew []), are holidays observed in Judaism and by JewsThis article focuses on practices of mainstre ...
are dependent on the dates of the new moons.
Intercalary months
In lunisolar calendars, an intercalary month occurs seven times in the 19 years of the
Metonic cycle
The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recu ...
, or on average every 2.7 years (19/7). In the
Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel. I ...
this is noted with a periodic extra month of
Adar
Adar ( he, אֲדָר ; from Akkadian ''adaru'') is the sixth month of the civil year and the twelfth month of the religious year on the Hebrew calendar, roughly corresponding to the month of March in the Gregorian calendar. It is a month of 29 d ...
in the early spring.
Blue moon
In the modern system of "traditional" American full moon names tied to the
solstice
A solstice is an event that occurs when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21. In many countr ...
and
equinox
A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and se ...
points, a supernumerary full moon in such a period is called a blue moon. The term "
blue moon
A blue moon is an additional full moon that appears in a subdivision of a year: the third of four full moons in a season.
The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon a ...
" used in this sense may date to as early as the 16th century, but it became well known in the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
due to the ''Farmers' Almanac'' (published since 1818).
According to the pattern of use in the ''Farmers' Almanac'', a "blue moon" is the third full moon in any period between either a solstice and an equinox, or between an equinox and a solstice, (calculated using the
mean tropical year
A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time fro ...
), which contains four full moons. These seasons are equal in length, unlike the astronomical ones, which vary in length depending on the Earth's speed in its
elliptical orbit round the Sun. To compare, in 1983 the equal-length mean-solar solar points and the ''actual'' astronomical (observed) dates are shown in the table below (all dates and times in GMT):
As a consequence of checking an inadequate number of old issues of the ''Farmers' Almanac'', the author of an article in the March 1946 issue of ''
Sky & Telescope
''Sky & Telescope'' (''S&T'') is a monthly American magazine covering all aspects of amateur astronomy, including the following:
*current events in astronomy and space exploration;
*events in the amateur astronomy community;
*reviews of astronomic ...
'' magazine wrongly concluded that the ''Farmers' Almanac'' had used "blue moon" to denote "the second full moon in any month which contains two full moons".
The mistaken rule was retracted and declared "erroneous" in a 1999 ''Sky & Telescope'' article, which gave the corrected rule, based on order in seasons.
Using the original meaning, "blue moons" occur with the same average frequency of intercalary months, 7 times in 19 years; the ''Farmers' Almanac'' system of full moon names effectively defines a functioning
luni-solar calendar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the ...
. Because the Sky & Telescope definition depends on calendar months and because February is shorter than a lunar month, the will be a higher frequency of blue moons under that definition (in years in which February squeezes in between two full moons), so that blue moons occur on average about 8 times in 19 years.
It is a rare phenomenon to see an unusual blue color of the moon (not necessarily a full moon) when viewing the moon. This phenomenon is caused by dust particles or smoke in the atmosphere, and was seen after the forest fires in Sweden and Canada in 1950 and 1951. In 1883, after the eruption of Krakatoa in Indonesia, the Moon was blue for almost two years. Other less violent volcanic explosions have been followed by blue moons. The blue Moon was also seen after the eruption of El Chichon in Mexico in 1983, Mount St. Helens in 1980, and Mount Pinatubo in 1991.
See also
*
Lunar eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth ...
*
Lunar effect
The lunar effect is a purported unproven correlation between specific stages of the roughly 29.5-day lunar cycle and behavior and physiological changes in living beings on Earth, including humans. In some cases the purported effect may depend on ...
*
Lunar phase
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
*
Near side of the Moon
The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a ...
*
Orbit of the Moon
The Moon orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the stars in about 27.32 days (a tropical month and sidereal month) and one revolution relative to the Sun in about 29.53 days (a s ...
Footnotes
References
External links
Moon phase calculatorMoon phases for any date(Full Moon cycle analysis from 1900 - 2050)
Moon Phase Calendar for any date
{{DEFAULTSORT:Full Moon
Phases of the Moon
Observational astronomy