The Wiccan Wheel of the Year, based on the solar calendar of Celtic and Gaelic Paganism has reigned as the “orthodox” view in Asatru since 1974, despite the fact that Celtic and Gaelic peoples did not know or venerate the Aesir. Almost all modern pagans ignore the moon entirely in their calendars.    The modern “accepted” Asatru view is there are four Heathen holy days, the Solstices and the Equinoxes. Asatru organizations have given ZERO historical evidence to back up their claims that these are the historical Heathen holy days.  This article will quote the sources, many saga references, three historical Heathen calendars to survive from the 8th, 9th, and 10th centuries, several rune calendar staffs, and the surviving evidence. To paraphrase the Swedish archaeologist Dr. Andreas Nordberg, those who insist on referring to Yule (or Jol) as the solstice, must be more interested in the solstice itself, than they are in sources for Norse religion. 
Three historical Heathen calendars from the 8th, 9th, and 10th centuries show that Full Moons after solstices and equinoxes marked the three major holidays: Winter Nights, Yule, and Sigurblot. The three historical Heahten calendars to survive in the written record are: Bede's De Temporum Ratione, ch15, written in 725 AD. Einhard's Vita Karoli Magni (written circa 830 AD), and the Iceland Althing recorded their calendar around 930 AD.
The Norse Calendar was recorded by the Iceland Althing circa 930 AD. However, this calendar lists twelve Norse moons (called “months” today, but one must understand, the Germanic word “manoth” (Old Saxon) or “manod” (Old Franconian) or “manuthr” (Old Norse) meant “cycle of the moon.”) The word “moon” is cognate to the word “month.” Therefore, the idea of fixed solar months having nothing to do with the moon was not a concept known to Heathens before Christianization and was different from their Heathen worldview. Since the Norse holy days were not recorded by the Iceland Althing, we must look to the Sagas, calendar staffs, and Eddaic references to glean the Norse holy days. The Iceland Althing in the 10th century was already largely christian.
The Historical Heathen Holidays:
The Ynglinga Saga (chapter 8), from the year 1225, lists the three great blots of the year: “Odin established the same law in his land that had been in force in Asaland… On winter day (first day of winter) there should be blot for a good year, and in the middle of winter for a good crop; and the third blot should be on summer day, a Victory-blot.” In Old Norse, “Sigurblot” means “Victory-Blot.” "As long as Heathenry lasted he was held three blots: one on Winter Nights, a second at mid-Winter, and the third at the start of summer." (Saga of St. Olav, ch 117). Therefore, we have three major Norse blots a year, that appear in the context of Ynglinga Saga (and other references) that were done publicly at Uppsala. Let’s examine the three: 1. Winter Nights - (Also called Haustblot in Norway, and Disablot in Iceland). In the Víga-Glúms saga, a Blot called Winter Nights (Old Norse: vetrnætr) at the onset of winter. Winter Nights or Vetrnætr was a specific time of year in medieval Scandinavia that referred to “the three days which begin the winter season.” Please note that the Sagas also call Winter Nights "Haustblot" and "Disablot." Winter Nights, or Haustblot, is on the full moon of Haustmanuthr, meaning "harvest moon."
2. Yule: (Or Mid-Winter). In Heimskringla, the saga of Hakon the Good, section 15 (circa 1230 AD) it says the following: “The first night of Yule was hǫkunótt, that is midwinter night, and Yule was held for three nights.” The context of Hakon the Good section 15 is that Hakon is trying to force the Heathens into Christianity, so he moved Yule to the same date as Christmas, which was then held on the Solstice on the Julian Calendar, December 25th. Pre-christian Heathen Yule was a three-day holiday that started on a full moon, not on a fixed solar date. “Mid-winter” means three full moons after the full moon that began Winter and three full moons before the full moon that begins summer. Mid-winter was not half way between the equinoxes on a day called the solstice. This does not mean that Scandinavian and Germanic peoples did not know of the Solstice. More on this below. While the Heathen Germanic Calendars all had two seasons of the year, the Heathen Year was divided into quarters by four specific full moons, all three full moons apart (accept on lunar leap years, when summer added a moon, so there would be 13 moons in a year).
3. Sigurblot. (the start of summer). See Ynglinga Saga 8 quote above, and this important passage, as Sigurblot is a Victory Blot, sacrifices for victory due to the coming raiding and war season of summer: Heimskringla Olaf’s Saga Helga 77 “In Sweden there was an age-old custom whilst they were still heathen that there should be a blot in Upsala during Goa (moon.) Then they would blot for peace and victory for their king. People from all over Sweden were to resort there.” Please note, all Germanic Heathens venerated the same full moon as the start of Summer. The Scandinavians called this “Sigurblot” but the Anglish, Frisians, and Franks called this Eostre. The Church doesn’t date “Easter” (Eostre) to the Equinox, but to “the first Sunday after the first full moon after the vernal Equinox.” (Bede De Temporum Ratione, ch 62) The church still dates Easter this way today, not by the Equinox alone but by the full moon. Just as Christian Easter can be in a five-week window after the Equinox, the same is true with Heathen Sigurblot. This also applies to Winter Nights and Yule, they can be close to or farther away from the Equinox or Solstice, pending the lunar cycle of each year. Now, lets move on to the dating of these holy days.
Bede states in De Temporum Ratione, Ch 15 (725 AD): "Thus, the moon by which they began their winter season was called “Winterfylleth”, a name compounded of the terms for winter and full moon, because from the full moon of that moon winter was thought to begin." It is very clear that the Anglish Winter Full Moon (corresponding to Norse Winter Nights) began on a full moon. This was the method of dating for all Germanic tribes.
Let me quote Bede again from De Temporum Ratione: "The peoples who welcomed the year in this method also assigned three moons to each season of the year. When however, an embolism occurred, that is, a year of thirteen lunar moons, they added the intercalated moon to the summer, so that in the case three moons in succession were called “Litha.” Such a year was known as “Thrilitha”, having four moons of summer and three of each of the other seasons. The division of the year though was into two seasons: Winter and Summer. Summer comprising six (or seven) moons when the days were longer than the nights, and winters six moons when the nights were longer than the days. Thus, the moon by which they began their winter season was called “Winterfylleth”, a name compounded of the terms for winter and full moon, because from the full moon of that moon winter was thought to begin." Bede makes it very clear here, the Germanic year had two seasons, comprising six moons, but the year was divided into four quarters, three (full) moons each. If Winter Full Moon begins Winter, then Yule would be three full moons after Winter Full Moon, and Summer Full Moon (Sigurblot) would be three full moons after Yule Full Moon, and Midsummer (in which Bede mentions zero rituals, like Ynglinga Saga mentions no Mid-Summer Norse ritual) was just a quarter year marker, three full moons after Summer Full Moon when Sigurblot was. The word "mid-winter" in a Heathen context therefore would mean "the full moon half way between the full moon starting winter, and the full moon starting summer."
We have more evidence of this Full Moon holy day concept, from Norse sources. The oldest evidence we have for a possible Scandinavian yuletide feast, was described by the 6th century Byzantine chronicler Procopius, who mentioned that the inhabitants of Scandinavia (Thule) celebrated Mid-Winter, after the winter solstice (Andreas Nordberg Jul, disting och förkyrklig tideräkning 2006: 156). We also have Theitmar of Merseberg’s testimony. The Chronicon of Thietmar of Merseburg Chapter 17 (circa 1000 AD): "As I have heard odd stories concerning their ancient mid-winter sacrifices, I will not allow this custom to be ignored. The middle of that kingdom is called Lederun (Lejre), in the region of Sjælland, all the people gathered every nine years in January, that is after we have celebrated the birth of the Lord [Christmas], and there they offered to their gods sacrifices…”
Yule was originally after the solstice, but due to Christian persecution was moved to the solstice. Hakon the Good Saga, chapter 15, is about Hakon the Good being the Christian King of all Norway, and eventually turning on Heathenry to make Norway Christian. The first recorded date of Christmas being celebrated on December 25th was in 336 AD, during the time of the Roman Emperor Constantine. A few years later, Pope Julius I officially declared that the birth of Jesus would be celebrated on the 25th of December annually. December 25th was declared Christmas because on the Julian Calendar (whom Pope Julian was responsible for codifying) it was the solstice.
Christian doctrine was clear in this matter. Jesus chose to be born on the shortest day of the year for symbolic reasons, according to the Church Fathers. An early Christmas sermon by Augustine (who died August 28, 430 AD): "Hence it is that He was born on the day which is the shortest in our earthly reckoning and from which subsequent days begin to increase in length. He, therefore, who bent low and lifted us up chose the shortest day, yet the one whence light begins to increase." Hakon the Good's Saga proves that Christmas was at a different time than Yule, despite the fact Christmas was on the solstice. Hakon the Good (died 961 AD) moved Heathen Yule to be at the same time as Christmas, then understood to be the solstice. (Please note, Christmas was on the solstice until the Julian Calendar was rectified by the Gregorian Calendar six centuries after Hakon the Good’s time, specifically in the year 1582, when December 21 would in most years be the solstice. Therefore, when Hakon the Good moved Yule to the same date as Christmas, he was moving it to the solstice, the same date Christians celebrated Christmas.) It is Christian, and not Heathen, to celebrate Yule on the Solstice. It follows the example of Hakon the Good, son of the first king of all Norway, who was a chrsitian and forced Christianity on Norway.
Chapter 15 of the saga "Hakon the Good": "King Hakon was a good Christian when he came to Norway; but as the whole country was heathen, with much heathen sacrifice, and as many great people, as well as the favour of the common people, were to be conciliated, he resolved to practice his Christianity in private. But he kept Sundays, and the Friday fasts, and some token of the greatest holy-days. He made a law that the festival of Yule should begin at the same time as Christian people held it, and that every man, under penalty, should brew a meal of malt into ale, and therewith keep the Yule holy as long as it lasted. Formerly the first night of Yule was hǫkunótt, that is midwinter night, and Yule was held for three nights. It was his intent, as soon as he had set himself fast in the land, and had subjected the whole to his power, to introduce Christianity. He went to work first by enticing to Christianity the men who were dearest to him; and many, out of friendship to him, allowed themselves to be baptized, and some laid aside performing blot. He dwelt long in the Throndhjem district, for the strength of the country lay there; and when he thought that, by the support of some powerful people there, he could set up Christianity he sent a message to England for a bishop and other teachers; and when they arrived in Norway, Hakon made it known that he would proclaim Christianity over all the land. The people of More and Raumsdal referred the matter to the people of Throndhjem. King Hakon then had several churches consecrated and put priests into them; and when he came to Throndhjem he summoned the bondes to a Thing and invited them to accept Christianity. They gave an answer to the effect that they would defer the matter until the Frosta-thing, at which there would be men from every district of the Throndhjem country, and then they would give their determination upon this difficult matter."
Andreas Nordberg, the world’s foremost scholar on Norse Holidays , makes clear in his book on the dating of Yule that “The pre-Christian Yule feast occurs at the first full moon after the first new moon following the winter solstice, while the disting took place at the third full moon according to the same method of calculation.”  At Yule it was determined if a thirteenth moon would be added to the year. To keep the following year’s Yule as the first full moon after the first new moon after the solstice, it would be determined if a 13th moon would be needed or not. You can see Nordberg's book, in PDF form, with a one page English Abstract (Introduction) and twenty page summary in English (the rest is in Swedish) here: https://www.academia.edu/1366945/Jul_disting_och_f%C3%B6rkyrklig_tider%C3%A4kning Nordberg also states, “Icelandic sources from the 13th century mention two months called Ylir or Jólmánur.”  This matches Bede in De Temporum Ratione, who mentions two moons of Giuli (Yule) in the Anglish Calendar. Nordberg also states that the Norse (like the Anglish) divided the year into quarters. “This division into quarters is not recorded in Nordic ecclesiastical calendars, but is evident in folktales, sagas, provincial laws, on rune-staffs and calendar rods and in other everyday contexts. The sources also hint at a process, during which this older system of dividing up the year was gradually replaced by a division based on important dates in the Church’s liturgical year. The exact dates (in the Julian calendar) for the older division into quarters vary somewhat in the sources. This is in part due to the fact that the start of each quarter was initially calculated as a three-day period; eventually this was normalized to one single day. However, the original three-day periods, expressed with West-Nordic names in the Julian calendar in the mid 12th century, appear to have been vinternätterna “the Winter Nights” of 13–15 October, midvinter “Midwinter” or midvinternatten “the Midwinter Night” 12–14 January, sommarmål “the first day(s) of summer” 13-15 April, and midsommar “Midsummer” 13–15 July.” (p.150) Please note that the later fixed solar dates were Christian dates. Pre-christian dates were entirely lunar based.
Modern Heathenry has followed the Wiccan calendar dating system, which has also impacted newly created rites with old names. Sumble, a Heathen ritual, is not done by modern Asatruar (most of the time) like it was done in Heimskringla, or Beowulf verses 489-675. The modern Sumble of one horn going around in a circle one person at a time, channeling energy, is a very obvious borrowing from Wicca. The circle is a Celtic circle, and I have attended many sumbles where the term "Celtic Circle" was used. (Wicca is a fine path, but it is not a Germanic or a historical Heathen path.) Please note, for one example, the world's largest Asatru organization: "The Asatru Community" does teach this clearly on their website. 
Here is the historical Frankish Heathen Calendar, recorded by Einhard in Vita Karolini Magni, chapter 29, translation mine: "He (Charlemagne) began a grammar of his native language. He gave the moons (months) names in his own tongue, in place of the Latin and barbarous names by which they were formerly known among the Franks. He likewise designated the winds by twelve appropriate names; there were hardly more than four distinctive ones in use before. He called January, Wintarmanoth; February, Hornung; March, Lentzinmanoth; April, Ostarmanoth; May, Winnemanoth; June, Brachmanoth; July, Heuvimanoth; August, Aranmanoth; September, Witumanoth; October, Windumemanoth; November, Herbistmanoth; December, Heilagmanoth."
Below (Figure1) is the Norse Heathen calendar which the Iceland Christian Althing recorded in the 10th century AD. I restored it to its pre-christian Heathen Calendar prior christianization due to the work of Andreas Nordberg (Nordberg, Andreas. 2006. Jul, disting och förkyrklig tideräkning: Kalendrar och kalendariska riter i det förkristna Norden. Kungl. Gustav Adolfs Akademien för svensk folkkultur: Uppsal). Please note the Iceland Althing followed Hakon the Good’s contemporary example of moving Yule to the same time as Christmas. Also, the calendar shows that the Heathens had two seasons: Winter and Summer. Figure1
Come visit us on Facebook: Search for the group "Aldsidu: Saxon Heathenry" Also, visit our page on Facebook called "Germanic Heathenry" where we are working together to tell the world who we are. Common Mistakes: **How did the Wiccan wheel of the year make it into US Asatru? Stephen McNallen founded the Viking Brotherhood in the early 1970s. This organization is the forerunner of the AFA (Asatru Folk Assembly.) McNallen circled with a Berkeley group called Freya's Folk, and adopted the Wiccan Wheel wholesale from them, around the same time he was appropriating the term "Asatru". As a Texan born to a Catholic family, McNallen did not have a previous pagan background before this exposure. Given that pretty much everything publicly practiced as Paganism was Wiccanate at this time, McNallen's adapted "Wiccatru" naturally became common "heathen" practice across the United States, even in Universalist groups. The "wheel of the year" was a collaboration between Gerald Gardner and Ross Nichols, woven into Gardner's mythic survival narrative. 1. Ostara is a Wiccan Sabbath, and therefore, while Heimskringla makes clear that Sigurblot is the most important Norse holy day, due to the Wiccanization of Asatru; most modern Norse Heathens (Asatruar) have never heard of Sigurblot, and erroneously believe that Ostara is a Norse Goddess, despite the fact she clearly is not mentioned in the Sagas, the Eddas, or the calendar recorded by the Iceland Althing circa 930 AD. It appears to me that Ostara is a continuation of Christian Easter, i.e. Yule (replacing xmas) and Ostara (replacing Easter) get the most press today. 2. Yule is most-often thought to be on the Solstice, but this is actually Christianity's attempt to stamp out Heathen Yule and replace it with Christ-Mass or Christmas, originally on the Julian Calendar's Winter Solstice (December 25th). Yule was on the Full Moon of Yule Moon, most of the time in January, but on a rare occassion, early February. 3. Midsummer was not a historical Heathen holiday. However, due to the Christian holiday of the birth of John the Baptist 6 months prior to Jesus (on the Julian Calendar's Summer Solstice of June 24th.) Therefore, today, a formerly Heathen word is applied to St. John's Day. Mid-summer was a time marker, but not a major blot in historical Heathen times. 4. People lump Halloween, with Celtic origins, with Germanic and Scandinavian Heathenry, i.e. 10/31 is often a blot day. 5. There is a huge lack of understanding on Winter Nights. It was the Norse New Year, and was also called "Disablot" and "Haustblot" in the sagas. It was on the full moon of Haustmanuthr. Yule and Winter Nights are hands down (by a landslide) the two most attested holidays in the Sagas. Haustblot or Winter Nights was on the full moon of Haustmanuthr (or Harvest Moon.) 6. Walpurgis Night. St. Walpurga was the neice of St. Boniface, who chopped down Thor's Oak of the Chatti. St. Walpurga preached the destruction of Saxon places of veneration (Sacred Groves, the Irminsul), and became a saint due to her persecution of Germanic Pagans, just like her Uncle St. Boniface persecuted and destroyed Heathen holy cites. I have a well footnoted article on the Christian origins of Walpurgis Night (https://www.aldsidu.com/post/asatru-s-most-embarrassing-time-of-the-year). I am personally "embarassed" at this common lack of knowledge, to have a "pagan day" named after such a person. The biggest reason why Aldsidu was founded, was to distance Aldsidu from the racism in Asatru, as well as such disappointing mis-information.  
Thank You: A big thanks to Professor Jon White of Crecganford. Please visit his YouTube channel called "Crecganford." Jon White has some amazing and well researched content on his YouTube channel, and I highly recommend it! https://www.youtube.com/channel/UChhMB_J0kz8eBJECy4d5uSQ
Footnotes:  A Book of Troth, 1988 by Edred Thorsson (Author), Joshua Buckley and Michael Moynihan (Editor). ISBN 978-1-4196-3598-4.  The Asatru Free Assembly, founded in 1974 by Stephen McNallen. The first attempt to provide a Germanic version of the Wiccan Wheel of the Year was made by McNallen in desktop-published documents between 1975-1976.  Mark Puryear, The Nature of Asatru: An Overview of the Ideals and Philosophy of the Indigenous Religion of Northern Europe, iUniverse, 2006, p. 214. Author Mark Puryear (2006), constructed an "eight-spoked Yule, also called achtwung", also paralleling the eight holidays in the Wheel of the Year in Wicca, but with slight differences to McNallen's 1970s version: Disting, Ostara, Beltaine, Midsummer, Hleifblot, Haustblot, Vetrablot, Yule. Of these eight names, Ostara, Beltaine, Midsummer and Yule coincide with the Wiccan "Wheel". The remaining four, Disting, Hleifblot, Haustblot and Vetrablot, correspond to Wiccan Imbolc, Lughnasadh, Mabon and Samhain, respectively. Puryear (p. 186) mentions "Charming of the Plow" it as an "alternate name" for Disting, which he in turn identifies with the "midwinter sacrifice".  https://www.theasatrucommunity.org/holidays  (Nordberg, Andreas. 2006. Jul, disting och förkyrklig tideräkning: Kalendrar och kalendariska riter i det förkristna Norden. Kungl. Gustav Adolfs Akademien för svensk folkkultur: Uppsal).  (Jul, disting och förkyrklig tideräkning Kalendrar och kalendariska riter i det förkristna Norden Uppsala 2006, P.4)
 (Jul, disting och förkyrklig tideräkning Kalendrar och kalendariska riter i det förkristna Norden Uppsala 2006, P.147)  https://www.theasatrucommunity.org/post/2018/03/16/the-importance-of-ritual-to-asatru (as of 9/20/2021.) "SUMBLE: At the first glance, a sumble appears to be quite simple. It primarily consists of a filled drinking horn being passed from person to person and each, in turn, making a toast. The subjects of said toasts can be the Gods, the ancestors, land spirits, heroes or members of the assembled folk. It is also seen as a good opportunity to boast about personal accomplishments that would be of interest to the gathering, or to take an oath if you have a need to take one. In sumble people are usually seated in a ring, and the horn usually moves around the circle multiple times, three rounds being most common. The horn may simply be passed from person to person, or somebody may be carrying the horn around the ring and offering it to each of the people in turn. If the horn is being carried, then the person doing so is usually referred to as the Valkyrie or the Hall-idis. This is a position of great honor, and it was a role that in old heathen times was most often filled by the wife of the host. Often, each round is given a topic, and all toasts made during that round should generally pertain to that topic. A common set of rounds is to toast to one of the Aesir or Vanir in the first round, to an ancestor or hero in the second, and then the third round would be for boasts, oaths, or just an open round if you do not have a boast or oath to make. If there are further rounds beyond the third they are usually open to whatever people feel like toasting. Of course, many kindreds use different systems than this, or may in fact use no system at all and just declare all rounds to be open. Despite it's apparent simplicity, the rite does have a great deal of metaphysical significance, and for that reason there is a great amount of tradition and taboo that has built up around it."
 https://www.brutenorse.com/blog/2017/12/norse-yuletide-sacrifices-had-almost.html  https://www.theasatrucommunity.org/walpurgis-and-mayday
 Gesta Hammabirgemsos ecclesiae pontificum (c.1073 AD)