document_title: A Song of Ice and Fire

question_text: how many books left in game of thrones

question_tokens: how many books left in game of thrones

text: A Song of Ice and Fire

text: Plot synopsis[edit]

text: A Song of Ice and Fire takes place in a fictional world in which seasons last for years and end unpredictably. Nearly three centuries before the events of the first novel (see backstory), the Seven Kingdoms of Westeros were united under the Targaryen dynasty by Aegon I and his sisters Visenya and Rhaenys, with Aegon Targaryen becoming the first king of the whole of the continent of Westeros, save for the southerly Dorne. At the beginning of A Game of Thrones, 15 peaceful years have passed since the rebellion led by Lord Robert Baratheon deposed and killed the last Targaryen king, Aerys II "the Mad King", and proclaimed Robert king of the Seven Kingdoms, with a nine year long summer coming to an end.

text: The principal story chronicles the power struggle for the Iron Throne among the great Houses of Westeros following the death of King Robert in A Game of Thrones. Robert's heir apparent, the 13-year old Joffrey, is immediately proclaimed king through the machinations of his mother, Queen Cersei Lannister. When Lord Eddard "Ned" Stark, Robert's closest friend and chief advisor, discovers that Joffrey and his siblings are the product of incest between Cersei and her twin brother Jaime "The Kingslayer" Lannister, Eddard attempts to unseat Joffrey but is betrayed and executed for treason. In response, Robert's brothers Stannis and Renly both lay separate claims to the throne. During this period of instability, two of the Seven Kingdoms of Westeros attempt to become independent from the Iron Throne: Eddard's eldest son Robb is proclaimed King in the North, while Lord Balon Greyjoy desires to recover the sovereignty of his region, the Iron Islands. The so-called "War of the Five Kings" is in full progress by the middle of the second book, A Clash of Kings.

text: The second story takes place in the far north of Westeros, where an 8,000-year-old wall of ice, simply called "the Wall", defends the Seven Kingdoms from the Others. The Wall's sentinels, the Sworn Brotherhood of the Night's Watch, also protect the realm from the incursions of the "wildlings" or "Free Folk", who are humans living north of the Wall. The Night's Watch story is told primarily through the point of view of Jon Snow, Eddard's bastard son.[8] Jon follows the footsteps of his uncle Benjen Stark and joins the Watch at a young age, rising quickly through the ranks, eventually becoming Lord Commander of the Night's Watch. In the third volume, A Storm of Swords, the Night's Watch storyline becomes increasingly entangled with the War of the Five Kings.

text: The third story follows Daenerys Targaryen, daughter of Aerys, the last Targaryen king. On the continent of Essos, east of Westeros across the Narrow Sea, Daenerys is married off by her elder brother Viserys Targaryen to a powerful warlord, but slowly becomes an independent and intelligent ruler in her own right. Her rise to power is aided by the historic birth of three dragons, hatched from eggs given to her as wedding gifts. The three dragons soon become not only a symbol of her bloodline and her legitimate claim to the throne, but also devastating weapons of war.

text: Publishing history[edit]

text: Overview[edit]

text: Books in the Ice and Fire series are first published in hardcover and are later re-released as paperback editions. In the UK, Harper Voyager publishes special slipcased editions.[9] The series has also been translated into more than 30 languages.[10] All page totals given below are for the US first editions.[why?]

text:
#
Title
Pages
Chapters
Words
Audio
US release

1
A Game of Thrones
694[11]
73
292,727[12]
33h 53m
August 1996[11]

2
A Clash of Kings
768[13]
70
318,903[14]
37h 17m
February 1999[13]

3
A Storm of Swords
973[15]
82
414,604[16]
47h 37m
November 2000[15]

4
A Feast for Crows
753[17]
46
295,032[18]
31h 10m
November 2005[17]

5
A Dance with Dragons
1040[19]
73
414,788[20]
48h 56m
July 2011[19]

6
The Winds of Winter
Forthcoming[21]

7
A Dream of Spring
Forthcoming[22]

Total
4,228
344
1,736,054
198h 53m

text: First three novels (1991–2000) [edit]

text: George R. R. Martin was already a successful fantasy and sci-fi author and TV writer before writing his A Song of Ice and Fire book series.[23] Martin had published his first short story in 1971 and his first novel in 1977.[24] By the mid-1990s, he had won three Hugo Awards, two Nebula Awards, and other awards for his short fiction.[25] Although his early books were well-received within the fantasy fiction community, his readership remained relatively small and Martin took on jobs as a writer in Hollywood in the mid-1980s.[25] He worked principally on the revival of The Twilight Zone throughout 1986 and on Beauty and the Beast until 1990, but he also developed his own TV pilots and wrote feature film scripts. He grew frustrated that his pilots and screenplays were not getting made[25] and that TV-related production limitations like budgets and episode lengths were forcing him to cut characters and trim battle scenes.[26] This pushed Martin back towards writing books, where he did not have to worry about compromising the size of his imagination.[25] Admiring the works of J. R. R. Tolkien in his childhood, he wanted to write an epic fantasy, though he did not have any specific ideas.[27]

text: When Martin was between Hollywood projects in the summer of 1991, he started writing a new science fiction novel called Avalon. After three chapters, he had a vivid idea of a boy seeing a man's beheading and finding direwolves in the snow, which would eventually become the first non-prologue chapter of A Game of Thrones.[28] Putting Avalon aside, Martin finished this chapter in a few days and grew certain that it was part of a longer story.[29] After a few more chapters, Martin perceived his new book as a fantasy story[29] and started making maps and genealogies.[23] However, the writing of this book was interrupted for a few years when Martin returned to Hollywood to produce his TV series Doorways that ABC had ordered but ultimately never aired.[26]

text:
"The first scene...chapter one of the first book, the chapter where they find the direwolf pups...just came to me out of nowhere. I was...at work on a different novel, and suddenly I saw that scene. It didn't belong in the novel I was writing, but it came to me so vividly that I had to sit down and write it, and by the time I did, it led to a second chapter, and the second chapter was the Catelyn chapter where Ned has just come back."

—George R. R. Martin in 2014[30]

tag: div

text: In 1994, Martin gave to his agent, Kirby McCauley, the first 200 pages and a two-page story projection as part of a planned trilogy with the novels A Dance with Dragons and The Winds of Winter intended to follow. When Martin had still not reached the novel's end at 1400 manuscript pages, he felt that the series needed to be four and eventually six books long,[26][31] which he imagined as two linked trilogies of one long story.[32] Martin chose A Song of Ice and Fire as the overall series title: Martin saw the struggle of the cold Others and the fiery dragons as one possible meaning for "Ice and Fire", whereas the word "song" had previously appeared in Martin's book titles A Song for Lya and Songs the Dead Men Sing, stemming from his obsessions with songs.[33] Martin also named Robert Frost's 1920 poem "Fire and Ice" and cultural associations such as passion versus betrayal as possible influences for the series' title.[34]

text: The revised finished manuscript for A Game of Thrones was 1088 pages long (without the appendices),[35] with the publication following in August 1996.[11] Wheel of Time author Robert Jordan had written a short endorsement for the cover that was influential in ensuring the book's and hence series' early success with fantasy readers.[36] Blood of the Dragon, a pre-release sample novella drawn from Daenerys's chapters, went on to win the 1997 Hugo Award for Best Novella.[37]

text: The 300 pages removed from the A Game of Thrones manuscript served as the opening of the second book, entitled A Clash of Kings.[31] It was released in February 1999 in the United States,[13] with a manuscript length (without appendices) of 1184 pages.[35] A Clash of Kings was the first book of the Ice and Fire series to make the best-seller lists,[26] reaching 13 on The New York Times Best Seller list in 1999.[38] After the success of The Lord of the Rings films, Martin received his first inquiries to the rights of the Ice and Fire series from various producers and filmmakers.[26]

text: Martin was several months late turning in the third book, A Storm of Swords.[25] The last chapter he had written was about the "Red Wedding", a pivotal scene notable for its violence (see Themes: Violence and death).[39] A Storm of Swords was 1521 pages in manuscript (without appendices),[35] causing problems for many of Martin's publishers around the world. Bantam Books published A Storm of Swords in a single volume in the United States in November 2000,[15] whereas some other-language editions were divided into two, three, or even four volumes.[35] A Storm of Swords debuted at number 12 in the New York Times bestseller list.[37][40]

text: Bridging the timeline gap (2000–2011) [edit]

text: After A Game of Thrones, A Clash of Kings, and A Storm of Swords, Martin originally intended to write three more books.[25] The fourth book, tentatively titled A Dance with Dragons, was to focus on Daenerys Targaryen's return to Westeros and the associated conflicts.[32] Martin wanted to set this story five years after A Storm of Swords so that the younger characters could grow older and the dragons grow larger.[41] Agreeing with his publishers early on that the new book should be shorter than A Storm of Swords, Martin set out to write the novel closer in length to A Clash of Kings.[35] A long prologue was to establish what had happened in the meantime, initially just as one chapter of Aeron Damphair on the Iron Islands at the Kingsmoot. Since the events on the Iron Islands were to have an impact in the book and could not be told with existing POV characters, Martin eventually introduced three new viewpoints.[42]

text: In 2001, Martin was still optimistic that the fourth installment might be released in the last quarter of 2002.[33] However, the five-year gap did not work for all characters during writing. On one hand, Martin was unsatisfied with covering the events during the gap solely through flashbacks and internal retrospection. On the other hand, it was implausible to have nothing happen for five years.[41] After working on the book for about a year, Martin realized he needed an additional interim book, which he called A Feast for Crows.[41] The book would pick up the story immediately after the third book, and Martin scrapped the idea of a five-year gap.[33] The material of the written 250-page prologue was mixed in as new viewpoint characters from Dorne and the Iron Islands.[42] These expanded storylines and the resulting story interactions complicated the plot for Martin.[43]

text: The manuscript length of A Feast for Crows eventually surpassed A Storm of Swords.[41] Martin was reluctant to make the necessary deep cuts to get the book down to publishable length, as that would have compromised the story he had in mind. Printing the book in "microtype on onion skin paper and giving each reader a magnifying glass" was also not an option for him.[35] On the other hand, Martin rejected the publishers' idea of splitting the narrative chronologically into A Feast for Crows, Parts One and Two.[7] Being already late with the book, Martin had not even started writing all characters' stories[44] and also objected to ending the first book without any resolution for its many viewpoint characters as in previous books.[41]

text: With the characters spread out across the world,[21] a friend suggested that Martin divide the story geographically into two volumes, of which A Feast for Crows would be the first.[7] This approach would give Martin the room to complete his commenced story arcs as he had originally intended,[35] which he still felt was the best approach years later.[21] Martin moved the unfinished characters' stories set in the east (Essos) and north (Winterfell and the Wall) into the next book, A Dance with Dragons,[45] and left A Feast for Crows to cover the events on Westeros, King's Landing, the Riverlands, Dorne, and the Iron Islands.[35] Both books begin immediately after the end of A Storm of Swords,[21] running in parallel instead of sequentially, and involve different casts of characters with only little overlap.[35] Martin split Arya's chapters into both books after having already moved the three other most popular characters (Jon Snow, Tyrion, and Daenerys) into A Dance with Dragons.[45]

text: Upon its release in October 2005 in the UK[46] and November 2005 in the US,[17] A Feast for Crows went straight to the top of The New York Times bestseller list.[47] Among the positive reviewers was Lev Grossman of Time, who dubbed Martin "the American Tolkien".[48] However, fans and critics alike were disappointed with the story split that left the fates of several popular characters unresolved after A Storm of Swords' cliffhanger ending.[49][50] With A Dance with Dragons said to be half-finished,[49] Martin mentioned in the epilogue of A Feast for Crows that the next volume would be released by the next year.[51] However, planned release dates were repeatedly pushed back. Meanwhile, HBO acquired the rights to turn Ice and Fire into a dramatic series in 2007[52] and aired the first of ten episodes covering A Game of Thrones in April 2011.[53]

text: With around 1600 pages in manuscript length,[1] A Dance with Dragons was eventually published in July 2011 after six years of writing,[26] longer in page count and writing time than any of the preceding four novels.[23][49] The story of A Dance with Dragons catches up and goes beyond A Feast for Crows around two-thirds into the book,[44] but nevertheless covers less story than Martin had intended, omitting at least one planned large battle sequence and leaving several character threads ending in cliff-hangers.[23] Martin attributed the delay mainly to his untangling "the Meereenese knot", which the interviewer understood as "making the chronology and characters mesh up as various threads converged on [Daenerys]".[50] Martin also acknowledged spending too much time on rewriting and perfecting the story, but soundly rejected the theories of some of his critics that he had lost interest in the series or would bide his time to make more money.[49]

text: Planned novels and future[edit]

text: Martin believes the last two volumes of the series will be big books of 1500 manuscript pages each.[54] The sixth book will be called The Winds of Winter,[55] taking the title of the last book of the originally planned trilogy.[21] Displeased with the provisional title A Time for Wolves for the final volume, Martin ultimately announced A Dream of Spring as the title for the seventh book in 2006.[22] Martin said in March 2012 that the final two novels will take readers farther north than any of the previous books, and that the Others will appear in the book.[56]

text: The Winds of Winter[edit]

text: The Winds of Winter will resolve the Dance with Dragons cliffhangers early on and "will open with the two big battles that [the fifth book] was building up to, the battle in the ice and the battle [...] of Slaver's Bay. And then take it from there."[56] By the middle of 2010, Martin had already finished five chapters of The Winds of Winter from the viewpoints of Sansa Stark, Arya Stark, Arianne Martell, and Aeron Greyjoy, accumulating to around 100 completed pages.[55][57] After the publication of A Dance with Dragons in 2011, Martin announced he would return to writing in January 2012.[23] He spent the meantime on book tours, conventions, and continued working on his The World of Ice & Fire companion guide and a new Tales of Dunk and Egg novella.[58][59]

text: In December 2011, Martin posted a chapter from The Winds of Winter from the viewpoint of Theon Greyjoy;[60] several other chapters have been made public since. Four hundred pages of the sixth novel have been written as of October 2012, although Martin considers only 200 as "really finished"; the rest needs revising.[34] In 2011, Martin gave three years as a realistic estimate for finishing the sixth book at a good pace,[1] but said ultimately the book "will be done when it's done",[21] acknowledging that his publication estimates had been too optimistic in the past.[23] Martin did not intend to separate the characters geographically again.[27]

text: In 2015 there were indications that the book would be published before the sixth season of the HBO show[61][62][63][64][65][66] but in early January 2016 Martin confirmed that he had not met an end-of-year deadline that he had established with his publisher for release of the book before the sixth season. He added that there was "a lot still left to write" and that completion of the book was "months away still...if the writing goes well." Martin also revealed there had been a previous deadline of October 2015 that he had considered achievable in May 2015, and that in September 2015 he had still considered the end-of-year deadline achievable. He further confirmed that some of the plot of the book might be revealed in the upcoming season of Game of Thrones.[67] In February 2016, Martin stated that he dropped all his editing projects except for Wild Cards, and that he would not be writing any teleplays, screenplays, short stories, introductions or forewords before delivering The Winds of Winter.[68]

text: During the Guadalajara International Book Fair in Mexico in early December 2016, Martin offered the following hint as to the tone of this book:

text: There are a lot of dark chapters right now ... I've been telling you for 20 years that winter was coming. Winter is the time when things die, and cold and ice and darkness fill the world, so this is not going to be the happy feel-good that people may be hoping for. Some of the characters [are] in very dark places.[69]

text: A Dream of Spring[edit]

text: Martin is firm about ending the series with the seventh novel "until I decide not to be firm".[23] With his stated goal of telling the story from beginning to end, he will not truncate the story to fit into an arbitrary number of volumes.[39] He knows the ending in broad strokes as well as the future of the main characters,[27] and will finish the series with bittersweet elements where not everyone will live happily ever after.[37] Martin hopes to write an ending similar to The Lord of the Rings that he felt gave the story a satisfying depth and resonance. On the other hand, Martin noted the challenge to avoid a situation like the finale of the TV series Lost, which left some fans disappointed by deviating too far from their own theories and desires.[21] In 2015, Martin said that he was not writing A Dream of Spring together with The Winds of Winter,[70] and in early 2016, he said he did not believe A Dream of Spring would be published before the last season of the HBO show.[71]

text: Martin offered the following hint as to how the series would conclude during a Q&A at the Guadalajara International Book Fair. "I'm not going to tell you how I'm going to end my book, but I suspect the overall flavor is going to be as much bittersweet as it is happy."[69]

text: TV series and other writings[edit]

text: Early during the development of the TV series, Martin told major plot points to producers David Benioff and D. B. Weiss.[27] (The New York Times reported in 2011 that, at age 62, Martin was by all accounts in robust health.)[72] Martin was confident he would have published at least The Winds of Winter before the TV series overtook him.[27] Nevertheless, there was general concern about whether Martin would be able to stay ahead of the show.[73] As a result, head writers Benioff and Weiss learned more future plot points from Martin in 2013 to help them set up the show's new possible seasons. This included the end stories for all the core characters. Deviations from the books' storylines are also being considered, but a two-year show hiatus to wait for new books is not an option for them as the child actors continue to grow and the show's popularity would wane.[74] Martin indicated he would not permit another writer to finish the book series.[49] On January 2, 2016, Martin confirmed that the sixth volume would not be published before the start of the sixth season of the HBO series.[75]

text: Regarding A Song of Ice and Fire as his magnum opus, Martin is certain never to write anything on this scale again and would only return to this fictional universe in the context of stand-alone novels.[42] He prefers to write stories about characters from other Ice and Fire periods of history such as his Tales of Dunk and Egg project, instead of continuing the series directly.[42][76] A possible future side project is a prequel set during Aegon's conquest of Westeros.[77] Martin said he would love to return to writing short stories, novellas, novelettes, and stand-alone novels from diverse genres such as science fiction, horror, fantasy, or even a murder mystery. However, he will see if his audience follows him after publishing his next project.[29][36]

text: Inspiration and writing[edit]

text: Genre[edit]

text: George R. R. Martin believes the most profound influences to be the ones experienced in childhood.[78] Having read H. P. Lovecraft, Robert E. Howard, Robert A. Heinlein, Eric Frank Russell, Andre Norton,[29] Isaac Asimov,[33] Fritz Leiber, and Mervyn Peake[79] in his youth, Martin never categorized these authors' literature into science fiction, fantasy, or horror and will write from any genre as a result.[78] Martin classified A Song of Ice and Fire as "epic fantasy",[1] and specifically named Tad Williams as very influential for the writing of the series.[33][79] One of his favorite authors is Jack Vance,[33] although Martin considered the series not particularly Vancean.[32]

text: Martin experienced some harsh winters when living in Dubuque a few years in the 70s, and suspects these winters had an influence on his writing; "I think a lot of the stuff in A Game of Thrones, the snow and ice and freezing, comes from my memories of Dubuque".[80]

text:
"[Martin's Ice and Fire series] was groundbreaking (at least for me) in all kinds of ways. Above all, the books were extremely unpredictable, especially in a genre where readers have come to expect the intensely predictable. [...] A Game of Thrones was profoundly shocking when I first read it, and fundamentally changed my notions about what could be done with epic fantasy."

—Fantasy writer Joe Abercrombie in 2008[81]

text: The medieval setting has been the traditional background for epic fantasy. However, where historical fiction leaves versed readers knowing the historical outcome,[79] original characters may increase suspense and empathy for the readers.[78] Yet Martin felt historical fiction, particularly when set during the Middle Ages, had an excitement, grittiness, and a realness to it that was absent in fantasy with a similar backdrop.[82] Thus, he wanted to combine the realism of historical fiction with the magic appeal of the best fantasies,[83] subduing magic in favor of battles and political intrigue.[25] He also decided to avoid the conventional good versus evil setting typical for the genre, using the fight between Achilles and Hector in Homer's Iliad, where no one stands out as either a hero or a villain, as an example of what he wants to achieve with his books.[84]

text: Martin is widely credited with broadening the fantasy fiction genre for adult content, including incest, paedophilia, and adultery.[49] For The Washington Post's Writing for The Atlantic, Amber Taylor assessed the novels as hard fantasy with vulnerable characters to which readers become emotionally attached.[85] CNN found in 2000 that Martin's mature descriptions were "far more frank than those found in the works of other fantasy authors",[86] although Martin assessed the fantasy genre to have become rougher-edged a decade later and that some writers' work was going beyond the mature themes of his novels.[39] Adam Roberts called Martin's series the most successful and popular example of the emerging subgenre of grimdark fantasy,[87] influencing other writers associated with that style, such as Joe Abercrombie.

text: Writing process[edit]

text: Setting out to write something on an epic scale,[86] Martin projected to write three books of 800 manuscript pages in the very early stages of the series.[79] His original 1990s contract specified one-year deadlines for his previous literary works, but Martin only realized later that his new books were longer and hence required more writing time.[41] In 2000, Martin planned to take 18 months to two years for each volume and projected the last of the planned six books to be released five or six years later.[37] However, with the Ice and Fire series evolving into the biggest and most ambitious story he has ever attempted writing,[45] he still has two more books to write as of 2016. Martin said he needed to be in his own office in Santa Fe, New Mexico to immerse himself in the fictional world and write.[25] As of 2011, Martin was still typing his fiction on a DOS computer with WordStar 4.0 software.[88] He begins each day at 10 am with rewriting and polishing the previous day's work,[78] and may write all day or struggle to write anything.[25] Excised material and previous old versions are saved to be possibly re-inserted at a later time.[45]

text: Martin set the Ice and Fire story in a secondary world inspired by Tolkien's writing.[27] Unlike Tolkien, who created entire languages, mythologies, and histories for Middle-earth long before writing The Lord of the Rings, Martin usually starts with a rough sketch of an imaginary world that he improvises into a workable fictional setting along the way.[49] He described his writing as coming from a subconscious level in "almost a daydreaming process",[89] and his stories, which have a mythic rather than a scientific core, draw from emotion instead of rationality.[29] Martin employs maps[25] and a cast list topping 60 pages in the fourth volume,[7] but keeps most information in his mind.[1] His imagined backstory remains subject to change until published, and only the novels count as canon.[45] Martin does not intend to publish his private notes after the series is finished.[25]

text: Martin drew much inspiration from actual history for the series,[78] having several bookcases filled with medieval history for research[90] and visiting historic European landmarks.[43] For an American who speaks only English, the history of England proved the easiest source of medieval history for him, giving the series a British rather than a German or Spanish historic flavor.[91] For example, Ned and Robb Stark resemble Richard, 3rd Duke of York and his son Edward IV, and Queen Cersei resembles both Margaret of Anjou[92] and Elizabeth Woodville.[93] Martin immersed himself in many diverse medieval topics such as clothing, food, feasting, and tournaments, to have the facts at hand if needed during writing.[37] The series was in particular influenced by the Hundred Years' War, the Crusades, the Albigensian Crusade, and the Wars of the Roses,[78][90] although Martin refrained from making any direct adaptations.[78] Martin was also inspired by the French historical novels The Accursed Kings by Maurice Druon, which are about the French monarchy in the 13th and 14th centuries.[2][3]

text: The story is written to follow principal landmarks with an ultimate destination, but leaves Martin room for improvisation. On occasion, improvised details significantly affected the planned story.[94] By the fourth book, Martin kept more private notes than ever before to keep track of the many subplots,[33] which became so detailed and sprawling by the fifth book as to be unwieldy.[23] Martin's editors, copy editors, and readers monitor for accidental mistakes,[33] although some errors have slipped into publication. For instance, Martin has inconsistently referred to certain characters' eye colors, and has described a horse as being of one sex and then another.[49]

text: Narrative structure[edit]

text:
Number of chapters per point-of-view character

[hide]POV character
Game
Clash
Storm
Feast
Dance
(Winds)
Sum

Bran Stark
7
7
4
–
3

21

Catelyn Stark
11
7
7
–
–

25

Daenerys Targaryen
10
5
6
–
10

31

Eddard Stark
15
–
–
–
–

15

Jon Snow
9
8
12
–
13

42

Arya Stark
5
10
13
3
2
≥1[55]
33

Tyrion Lannister
9
15
11
–
12
≥2[95]
47

Sansa Stark
6
8
7
3
–
≥1[55]
24

Davos Seaworth
–
3
6
–
4

13

Theon Greyjoy
–
6
–
–
7
≥1[60]
13

Jaime Lannister
–
–
9
7
1

17

Samwell Tarly
–
–
5
5
–

10

Cersei Lannister
–
–
–
10
2

12

Brienne of Tarth
–
–
–
8
–

8

Aeron Greyjoy
–
–
–
2
–
≥1[57]
2

Areo Hotah
–
–
–
1
1
≥1[96]
2

Asha Greyjoy
–
–
–
1
3

4

Arys Oakheart
–
–
–
1
–

1

Victarion Greyjoy
–
–
–
2
2
≥1[95]
4

Arianne Martell
–
–
–
2
–
≥2[55]
2

Quentyn Martell
–
–
–
–
4

4

Jon Connington
–
–
–
–
2

2

Melisandre
–
–
–
–
1

1

Barristan Selmy
–
–
–
–
4
≥2[97][98]
4

Prologue/Epilogue
1/–
1/–
1/1
1/–
1/1
1/
7

Total (characters)
73 (9)
70 (10)
82 (12)
46 (13)
73 (18)
TBD
344 (31)

text: The books are divided into chapters, each one narrated in the third person limited through the eyes of a point of view character,[49] an approach Martin learned himself as a young journalism student.[99] Beginning with nine POV characters in A Game of Thrones, the number of POV characters grows to a total of 31 in A Dance with Dragons (see table). The short-lived one-time POV characters are mostly restricted to the prologue and epilogue.[37] David Orr of The New York Times noted the story importance of "the Starks (good guys), the Targaryens (at least one good guy, or girl), the Lannisters (conniving), the Greyjoys (mostly conniving), the Baratheons (mixed bag), the Tyrells (unclear) and the Martells (ditto), most of whom are feverishly endeavoring to advance their ambitions and ruin their enemies, preferably unto death".[100] However, as Time's Lev Grossman noted, readers "experience the struggle for Westeros from all sides at once", such that "every fight is both triumph and tragedy [...] and everybody is both hero and villain at the same time".[101]

text: Modeled on The Lord of the Rings, the Ice and Fire story begins with a tight focus on a small group (with everyone in Winterfell, except Daenerys) and then splits into separate stories. The storylines are to converge again, but finding the turning point in this complex series has been difficult for Martin and has slowed down his writing.[21] Depending on the interview, Martin is said to have reached the turning point in A Dance with Dragons,[21] or to not quite have reached it yet in the books.[102] The series' structure of multiple POVs and interwoven storylines was inspired by Wild Cards, a multi-authored shared universe book series edited by Martin since 1985.[103] As the sole author, Martin begins each new book with an outline of the chapter order and may write a few successive chapters from a single character's viewpoint instead of working chronologically. The chapters are later rearranged to optimize character intercutting, chronology, and suspense.[37]

text: Influenced by his television and film scripting background, Martin tries to keep readers engrossed by ending each Ice and Fire chapter with a tense or revelational moment, a twist or a cliffhanger, similar to a TV act break.[104] Scriptwriting has also taught him the technique of "cutting out the fat and leaving the muscle", which is the final stage of completing a book, a technique that brought the page count in A Dance with Dragons down almost eighty pages.[105] Dividing the continuous Ice and Fire story into books is much harder for Martin. Each book shall represent a phase of the journey that ends in closure for most characters. A smaller portion of characters is left with clear-cut cliffhangers to make sure readers come back for the next installment, although A Dance with Dragons had more cliffhangers than Martin originally intended.[27][37] Both one-time and regular POV characters are designed to have full character arcs ending in tragedy or triumph,[37] and are written to hold the readers' interest and not be skipped in reading.[79] Main characters are killed off so that the reader will not rely on the hero to come through unscathed and will instead feel the character's fear with each page turn.[36]

text: The unresolved larger narrative arc encourages speculation about future story events.[49] According to Martin, much of the key to Ice and Fire's future lies over a dozen years in the fictional past, of which each volume reveals more.[25] Events planned from the beginning are foreshadowed, although Martin is careful not to make the story predictable.[102] The viewpoint characters, who serve as unreliable narrators,[21] may clarify or provide different perspectives on past events.[106] Therefore, what the readers believe to be true may not necessarily be true.[25]

text: Character development[edit]

text: Regarding the characters as the heart of the story,[107] Martin planned the epic Ice and Fire fantasy to have a large cast of characters and many different settings from the beginning.[21] A Feast for Crows has a 63-page list of characters,[7] with many of the thousands of characters mentioned only in passing[49] or disappearing from view for long stretches.[108] When Martin adds a new family to the ever-growing number of genealogies in the appendices, he devises a secret about the personality or fate of the family members. However, their backstory remains subject to change until written down in the story.[45] Martin drew most character inspiration from history (without directly translating historical figures)[25] and his own experiences, but also from the manners of his friends, acquaintances, and people of public interest.[33] Martin aims to "make my characters real and to make them human, characters who have good and bad, noble and selfish well-mixed in their natures".[37] Jeff VanderMeer of the Los Angeles Times remarked that "Martin's devotion to fully inhabiting his characters, for better or worse, creates the unstoppable momentum in his novels and contains an implied criticism of Tolkien's moral simplicity"[109] (see Themes: Moral ambiguity).

text: Martin deliberately ignored the writing rule of never giving two characters names starting with the same letter.[45] Instead, character names reflect the naming systems in various European family histories, where particular names were associated with specific royal houses and where even the secondary families assigned the same names repeatedly.[45] The Ice and Fire story therefore has children called "Robert" in honor of King Robert of House Baratheon, a "Brandon" in every other generation of the Starks in commemoration of Brandon the Builder (of the Wall), and the syllable "Ty" commonly occurring in given names of House Lannister.[31] Confident that readers would pay attention, Martin distinguished people sharing a given name[45] by adding numbers or locations to their given names (e.g. Henry V of England).[31] The family names were designed in association with ethnic groups (see backstory): the First Men in the North of Westeros had very simply descriptive names like Stark and Strong, whereas the descendants of the Andal invaders in the South have more elaborate, undescriptive house names like Lannister or Arryn, and the Targaryens and Valyrians from the Eastern continent have the most exotic names with the letter Y.[31]

text: All characters are designed to speak with their own internal voices to capture their views of the world.[37] The Atlantic pondered whether Martin ultimately intended the readers to sympathize with characters on both sides of the Lannister–Stark feud long before plot developments force them to make their emotional choices.[110] Contrary to most conventional epic fantasies, the Ice and Fire characters are vulnerable so that, according to The Atlantic, the reader "cannot be sure that good shall triumph, which makes those instances where it does all the more exulting."[85] Martin gets emotionally involved in the characters' lives during writing, which makes the chapters with dreadful events sometimes very difficult to write.[37] Seeing the world through the characters' eyes requires a certain amount of empathy with them, including the villains,[78] all of whom he has said he loves as if they were his own children.[79][107] Martin found that some characters had minds of their own and took his writing in different directions. He returns to the intended story if it does not work out, but these detours sometimes prove more rewarding for him.[45]

text: Arya Stark, Tyrion Lannister, Jon Snow, and Daenerys Targaryen generate the most feedback from readers.[111] Martin has stated that Tyrion is his personal favorite, as the grayest of the gray characters, with his cunning and wit making him the most fun to write.[79] Martin has also said that Bran Stark is the hardest character to write. As the character most deeply involved in magic, Bran's story needs to be handled carefully within the supernatural aspects of the books. Bran is also the youngest viewpoint character,[37] and has to deal with the series' adult themes like grief, loneliness, and anger.[104] Martin set out to have the young characters grow up faster between chapters, but, as it was implausible for a character to take two months to respond, a finished book represents very little time passed. Martin hoped the planned five-year break would ease the situation and age the children to almost adults in terms of the Seven Kingdoms, but he later dropped the five-year gap (see section Bridging the timeline gap).[27][37]

text: Themes[edit]

text: Although modern fantasy may often embrace strangeness, the Ice and Fire series is generally praised for what is perceived as a sort of medieval realism.[100] Believing that magic should be used moderately in the epic fantasy genre,[26] Martin set out to make the story feel more like historical fiction than contemporary fantasy, with less emphasis on magic and sorcery and more on battles, political intrigue, and the characters.[25] Though the amount of magic has gradually increased throughout the story, the series is still to end with less overt magic than most contemporary fantasies.[37] In Martin's eyes, literary effective magic needs to represent strange and dangerous forces beyond human comprehension,[59] not advanced alien technologies or formulaic spells.[112] As such, the characters understand only the natural aspects of their world, but not the magical elements like the Others.[100]

text: Since Martin drew on historical sources to build the Ice and Fire world,[78] Damien G. Walter of The Guardian saw a strong resemblance between Westeros and England in the period of the Wars of the Roses.[113] The Atlantic's Adam Serwer regarded A Song of Ice and Fire as "more a story of politics than one of heroism, a story about humanity wrestling with its baser obsessions than fulfilling its glorious potential", where the emergent power struggle stems from the feudal system's repression and not from the fight between good and evil.[110] Martin not only wanted to reflect the frictions of the medieval class structures in the novels, but also explore the consequences of the leaders' decisions, as general goodness does not automatically make competent leaders and vice versa.[83]

text: A common theme in the fantasy genre is the battle between good and evil,[83] which Martin rejects for not mirroring the real world.[32] Attracted to gray characters,[114] Martin instead endorses William Faulkner's view that only the human heart in conflict with itself was worth writing about.[83] Martin explores the questions of redemption and character change in the Ice and Fire series.[115] The multiple viewpoint structure allows characters to be explored from many sides, such that the supposed villains can provide their viewpoint.[86][42]

text: Although fantasy comes from an imaginative realm, Martin sees an honest necessity to reflect the real world where people die sometimes ugly deaths, even beloved people.[37] Main characters are killed off so that the reader will not expect the supposed hero to survive, and instead will feel the same tension and fear that the characters might.[36] The novels also reflect the substantial death rates in war.[79] The deaths of supernumerary extras or orcs have no major effect on readers, whereas a friend's death has much more emotional impact.[102] Martin prefers a hero's sacrifice to say something profound about human nature.[27]

text: According to Martin, the fantasy genre rarely focuses on sex and sexuality,[37] instead often treating sexuality in a juvenile way or neglecting it completely.[78] Martin, however, considers sexuality an important driving force in human life that should not be excluded from the narrative.[115] Providing sensory detail for an immersive experience is more important than plot advancement for Martin,[21] who aims to let the readers experience the novels' sex scenes, "whether it's a great transcendent, exciting, mind blowing sex, or whether it's disturbing, twisted, dark sex, or disappointing perfunctory sex."[115] Martin was fascinated by medieval contrasts where knights venerated their ladies with poems and wore their favors in tournaments while their armies mindlessly raped women in wartime.[37] The non-existent concept of adolescence in the Middle Ages served as a model for Daenerys' sexual activity at the age of 13 in the books.[104] The novels also allude to the incestuous practices in the Ptolemaic dynasty of Ancient Egypt to keep their bloodlines pure.[116]

text: Martin provides a variety of female characters to explore the place of women in a patriarchal society.[102] Writing all characters as human beings with the same basic needs, dreams, and influences,[24] his female characters are to cover the same wide spectrum of human traits as the males.[102][24]

text: Reception[edit]

text: Critical response[edit]

text: Science Fiction Weekly stated in 2000 that "few would dispute that Martin's most monumental achievement to date has been the groundbreaking A Song of Ice and Fire historical fantasy series",[37] for which reviews have been "orders of magnitude better" than for his previous works, as Martin described to The New Yorker.[49] In 2007, Weird Tales magazine described the series as a "superb fantasy saga" that "raised Martin to a whole new level of success".[29] Shortly before the release of A Dance with Dragons in 2011, Bill Sheehan of The Washington Post was sure that "no work of fantasy has generated such anticipation since Harry Potter's final duel with Voldemort",[108] and Ethan Sacks of Daily News saw the series turning Martin into a darling of literary critics as well as mainstream readers, which was "rare for a fantasy genre that's often dismissed as garbage not fit to line the bottom of a dragon's cage".[60] Salon.com's Andrew Leonard stated:

text: The success is all the more remarkable because [the series debuted] without mass market publicity or any kind of buzz in the fantasy/SF scene. George R. R. Martin earned his following the hard way, by word of mouth, by hooking his characters into the psyche of his readers to an extent that most writers of fantasy only dream of.[117]

text: Publishers Weekly noted in 2000 that "Martin may not rival Tolkien or Robert Jordan, but he ranks with such accomplished medievalists of fantasy as Poul Anderson and Gordon Dickson."[15] After the fourth volume came out in 2005, Time's Lev Grossman considered Martin a "major force for evolution in fantasy" and proclaimed him "the American Tolkien", explaining that, although Martin was "[not] the best known of America's straight-up fantasy writers" at the time and would "never win a Pulitzer or a National Book Award ... his skill as a crafter of narrative exceeds that of almost any literary novelist writing today".[48] As Grossman said in 2011, the phrase American Tolkien "has stuck to [Martin], as it was meant to",[101] being picked up by the media including The New York Times ("He's much better than that"),[118] the New Yorker,[49] Entertainment Weekly ("an acclaim that borders on fantasy blasphemy"),[23] The Globe and Mail,[51] and USA Today.[114] Time magazine named Martin one of the 100 most influential people in the world in 2011,[51] and USA Today named George R.R. Martin their Author of the Year 2011.[119]

text: According to The Globe and Mail's John Barber, Martin manages simultaneously to master and transcend the genre so that "Critics applaud the depth of his characterizations and lack of cliché in books that are nonetheless replete with dwarves and dragons".[51] Publishers Weekly gave favorable reviews to the first three Ice and Fire novels at their points of release, saying that A Game of Thrones had "superbly developed characters, accomplished prose and sheer bloody-mindedness",[11] that A Clash of Kings was "notable particularly for the lived-in quality of [their fictional world and] for the comparatively modest role of magic",[13] and that A Storm of Swords was one "of the more rewarding examples of gigantism in contemporary fantasy".[15] However, they found that A Feast For Crows as the fourth installment "sorely misses its other half. The slim pickings here are tasty, but in no way satisfying."[17] Their review for A Dance with Dragons repeated points of criticism for the fourth volume, and said that, although "The new volume has a similar feel to Feast", "Martin keeps it fresh by focusing on popular characters [who were] notably absent from the previous book."[19]

text: According to the Los Angeles Times, "Martin's brilliance in evoking atmosphere through description is an enduring hallmark of his fiction, the settings much more than just props on a painted stage", and the novels captivate readers with "complex storylines, fascinating characters, great dialogue, perfect pacing, and the willingness to kill off even his major characters".[109] CNN remarked that "the story weaves through differing points of view in a skillful mix of observation, narration and well-crafted dialogue that illuminates both character and plot with fascinating style",[86] and David Orr of The New York Times found that "All of his hundreds of characters have grace notes of history and personality that advance a plot line. Every town has an elaborately recalled series of triumphs and troubles."[100] Salon.com's Andrew Leonard "couldn't stop reading Martin because my desire to know what was going to happen combined with my absolute inability to guess what would happen and left me helpless before his sorcery. At the end, I felt shaken and exhausted."[120] The Christian Science Monitor advised reading the novels with an A Song of Ice and Fire encyclopedia at hand to "catch all the layered, subtle hints and details that [Martin] leaves throughout his books. If you pay attention, you will be rewarded and questions will be answered."[121]

text: Among the most critical voices were Sam Jordison and Michael Hann, both of The Guardian. Jordison detailed his misgivings about A Game of Thrones in a 2009 review and summarized "It's daft. It's unsophisticated. It's cartoonish. And yet, I couldn't stop reading .... Archaic absurdity aside, Martin's writing is excellent. His dialogue is snappy and frequently funny. His descriptive prose is immediate and atmospheric, especially when it comes to building a sense of deliciously dark foreboding [of the long impending winter]."[122] Hann did not consider the novels to stand out from the general fantasy genre, despite Martin's alterations to fantasy convention, although he rediscovered his childhood's views:

text: That when things are, on the whole, pretty crappy [in the real world], it's a deep joy to dive headfirst into something so completely immersive, something from which there is no need to surface from hours at a time. And if that immersion involves dragons, magic, wraiths from beyond death, shapeshifting wolves and banished princes, so be it.[123]

text: Sales[edit]

text: The reported overall sales figures of the A Song of Ice and Fire series vary. The New Yorker said in April 2011 (before the publication of A Dance with Dragons) that more than 15 million Ice and Fire books had been sold worldwide,[49] a figure repeated by The Globe and Mail in July 2011.[51] Reuters reported in September 2013 that the books including print, digital and audio versions have sold more than 24 million copies in North America.[125] The Wall Street Journal reported more than six million sold copies in North America by May 2011.[126] USA Today reported 8.5 million copies in print and digital overall in July 2011,[127] and over 12 million sold copies in print in December 2011.[119] The series has been translated into more than 20 languages;[10] USA Today reported the fifth book to be translated into over 40 languages.[114] Forbes estimated that Martin was the 12th highest-earning author worldwide in 2011 at $15 million.[128]

text: Martin's publishers initially expected A Game of Thrones to be a best-seller,[23] but the first installment did not even reach any lower positions in bestseller list.[58] This left Martin unsurprised, as it is "a fool's game to think anything is going to be successful or to count on it".[107] However, the book slowly won the passionate advocacy of independent booksellers and the book's popularity grew by word of mouth.[49] The series' popularity skyrocketed in subsequent volumes,[23] with the second and third volume making The New York Times Best Seller lists in 1999[38] and 2000,[40] respectively. The series gained Martin's old writings new attention, and Martin's American publisher Bantam Spectra was to reprint his out-of-print solo novels.[37]

text: The fourth installment, A Feast for Crows, was an immediate best-seller at its 2005 release,[23] hitting number one on "The New York Times" hardcover fiction bestseller list November 27, 2005, which for a fantasy novel suggested that Martin's books were attracting mainstream readers.[1] The paperback edition of A Game of Thrones reached its 34th printing in 2010, surpassing the one million mark.[129] Before it even premiered, the TV series had boosted sales of the book series, with Ice and Fire approaching triple-digit growth in year-on-year sales. Bantam was looking forward to seeing the tie-ins boost sales further,[53] and Martin's British publisher Harper Voyager expected readers to rediscover their other epic fantasy literature.[130] With a reported 4.5 million copies of the first four volumes in print in early 2011,[53] the four volumes re-appeared on the paperback fiction bestseller lists in the second quarter of 2011.[124][131]

text: At its point of publication in July 2011, A Dance with Dragons was in its sixth print with more than 650,000 hardbacks in print.[132] It also had the highest single and first-day sales of any new fiction title published in 2011 at that point, with 170,000 hardcovers, 110,000 e-books, and 18,000 audio books reportedly sold on the first day.[127] A Dance with Dragons reached the top of The New York Times bestseller list on July 31, 2011.[7] Unlike most other big titles, the fifth volume sold more physical than digital copies early on,[72] but nevertheless, Martin became the tenth author to sell 1 million Amazon Kindle e-books.[133] All five volumes and the four-volume boxed set were among the top 100 best-selling books in the United States in 2011 and 2012.[134]

text: The TV series has contributed significantly boosting sales of both the books and collectibles like box-sets, merchandise, and other items. The TV series also contributed in increasing the geographic coverage of the books, introducing new customers in emerging countries like India and Brazil to the book series. All this has significantly increased the overall book sales.

text: Fandom[edit]

text: During the 1980s and early 1990s, Martin's novels had slowly earned him a reputation in science fiction circles,[135] although he said to only have received a few fans' letters a year in the pre-internet days.[78] The publication of A Game of Thrones caused Martin's following to grow, with fan sites springing up and a Trekkie-like society of followers evolving that meet regularly.[135] Westeros.org, one of the main Ice and Fire fansites with about seventeen thousand registered members as of 2011, was established in 1999 by a Swedish-based fan of Cuban-American descent, Elio M. García, Jr., and his girlfriend; their involvement with Martin's work has now become semi-professional.[49] The Brotherhood Without Banners, an unofficial fan club operating globally, was formed in 2001. Their founders and other longtime members are among Martin's good friends.[49]

text: Martin runs an official website[7] and administers a lively blog with the assistance of Ty Franck.[49] He also interacts with fandom by answering emails and letters, although he stated in 2005 that their sheer numbers might leave them unanswered for years.[78] Since there are different types of conventions nowadays, he tends to go to three or four science-fiction conventions a year simply to go back to his roots and meet friends.[136] He does not read message boards anymore, so that his writing will not be influenced by fans foreseeing twists and interpreting characters differently from what he intended.[136]

text:
"After all, as some of you like to point out in your emails, I am sixty years old and fat, and you don't want me to 'pull a Robert Jordan' on you and deny you your book. Okay, I've got the message. You don't want me doing anything except A Song of Ice and Fire. Ever. (Well, maybe it's okay if I take a leak once in a while?)"

—George R. R. Martin on his blog in 2009[137]

text: While Martin calls the majority of his fans "great", and enjoys interacting with them,[27] some of them turned against him because of the six years it took to release A Dance with Dragons.[49] A movement of disaffected fans called GRRuMblers formed in 2009, creating sites such as Finish the Book, George and Is Winter Coming?.[49][51] When fans' vocal impatience for A Dance with Dragons peaked shortly after, Martin issued a statement called "To My Detractors"[137] on his blog that received media attention.[49][122][138] The New York Times noted that it was not uncommon for Martin to be mobbed at book signings either.[135] The New Yorker called this "an astonishing amount of effort to devote to denouncing the author of books one professes to love. Few contemporary authors can claim to have inspired such passion."[49]

text: Awards and nominations[edit]

text:
A Game of Thrones (1996) – Locus Award winner,[139] World Fantasy Award[140] and Nebula Award nominee, 1997[141]
A Clash of Kings (1998) – Locus Award winner,[139] Nebula Award nominee, 1999[141]
A Storm of Swords (2000) – Locus Award winner,[139] Hugo Award[142] and Nebula Awards nominee, 2001[143]
A Feast for Crows (2005) – Hugo,[144] Locus,[139] and British Fantasy Awards nominee, 2006[145]
A Dance with Dragons (2011) – Locus Award winner,[146] Hugo Award[147] and World Fantasy Award nominee, 2012[148]

text: Derived works[edit]

text: Novellas[edit]

text: Martin has written several prequel novellas. The Tales of Dunk and Egg series, three novellas set ninety years before the events of the novel series, feature the adventures of Ser Duncan the Tall and his squire "Egg", the later King Aegon V Targaryen. The stories have no direct connection to the plot of A Song of Ice and Fire, although both characters are mentioned in A Storm of Swords and A Feast For Crows, respectively. The first installment, The Hedge Knight, was published in the 1998 anthology Legends. The Sworn Sword followed in 2003, published in Legends II.[42] Both were later adapted into graphic novels.[149] The third novella, titled The Mystery Knight, was first published in the 2010 anthology Warriors,[150] and is planned to be adapted as a graphic novel as well.[151] Martin planned to release the first three novellas as one collection in 2014.[152] Up to eight further Dunk and Egg installments are planned.[39]

text: The novella The Princess and the Queen or, the Blacks and the Greens appeared in Tor Books's 2013 anthology Dangerous Women, and explains some of the Targaryen backstory two centuries before the events of the novels.[153][154] The Rogue Prince, or, the King's Brother, published in the 2014 anthology Rogues, is itself a prequel to the events of The Princess and the Queen.[155]

text: Chapter sets from the novels were also compiled into three novellas that were released between 1996 and 2003 by Asimov's Science Fiction and Dragon:

text:
Blood of the Dragon (July 1996),[156] taken from the Daenerys chapters in A Game of Thrones.
Path of the Dragon (December 2000),[157] taken from the Daenerys chapters in A Storm of Swords.
Arms of the Kraken (March 2003),[158] based on the Iron Islands chapters from A Feast for Crows.

text: TV series[edit]

text: With the popularity of the series growing, HBO optioned A Song of Ice and Fire for a television adaptation in 2007.[52] A pilot episode was produced in late 2009, and a series commitment for nine further episodes was made in March 2010.[159] The series, titled Game of Thrones, premiered in April 2011 to great acclaim and ratings (see Game of Thrones: Reception). The network picked up the show for a second season covering A Clash of Kings two days later.[160] Shortly after the conclusion of the first season, the show received 13 Emmy Award nominations, including Outstanding Drama Series, winning Outstanding Main Title Design and Outstanding Supporting Actor in a Drama Series for Peter Dinklage's portrayal of Tyrion Lannister.[161] HBO announced a renewal for a third season in April 2012, ten days after the season 2 premiere.[162] Due to the length of the corresponding book, the third season only covered roughly the first half of A Storm of Swords.[163]

text: Shortly after the season 3 premiere in March 2013, the network announced that Game of Thrones would be returning for a fourth season, which would cover the second half of A Storm of Swords along with the beginnings of A Feast for Crows and A Dance With Dragons.[164] Game of Thrones was nominated for 15 Emmy Awards for season 3.[165] Two days after the fourth season premiered in April 2014, HBO renewed Game of Thrones for a fifth and sixth season.[166] Season 5 premiered on April 12, 2015 and set a Guinness World Records for winning the highest number of Emmy Awards for a series in a single season and year, winning 12 out of 24 nominations, including Outstanding Drama Series.[167][168] These episodes were watched by 8 million viewers, setting a record number for the series.[169] The sixth season premiered on April 24, 2016.[170] These episodes received the most nominations for the 68th Primetime Emmy Awards with 23, winning 12, including the award for Outstanding Drama Series.[171]

text: Other works[edit]

text: A Song of Ice and Fire spawned an industry of spin-off products. Fantasy Flight Games released a collectible card game, a board game, and two collections of artwork inspired by the Ice and Fire series.[172][173] Various roleplaying game products were released by Guardians of Order and Green Ronin.[174][175] Dynamite Entertainment adapted A Game of Thrones into a same-titled monthly comic in 2011.[176] Several video games are available or in production, including A Game of Thrones: Genesis (2011) and Game of Thrones (2012) by Cyanide;[177][178] both received mediocre ratings from critics.[179] A social network game titled Game of Thrones Ascent (2013) by Disruptor Beam allows players to live the life of a noble during the series' period setting.[180] Random House released an official map book called The Lands of Ice and Fire, which includes old and new maps of the Ice and Fire world.[181] The companion book The World of Ice & Fire by Martin and the Westeros.org owners Elio M. García Jr. and Linda Antonsson was published in October 2014.[49] Other licensed products include full-sized weapon reproductions,[182] a range of collectable figures,[183][184] Westeros coinage reproductions,[185] and a large number of gift and collectible items based on the HBO television series.[186] The popularity of the HBO series has made its version of the Iron Throne an icon of the entire media franchise.[187][188][189][190]


document_title: Earth's magnetic field

question_text: earth's magnetism is due to which effect

question_tokens: earth 's magnetism is due to which effect

root

text: Earth's magnetic field

text: Importance[edit]

text: The Earth's magnetic field serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation.[4] One stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds.[5] Calculations of the loss of carbon dioxide from the atmosphere of Mars, resulting from scavenging of ions by the solar wind, indicate that the dissipation of the magnetic field of Mars caused a near total loss of its atmosphere.[6][7]

tag: p

text: The study of past magnetic field of the Earth is known as paleomagnetism.[8] The polarity of the Earth's magnetic field is recorded in igneous rocks, and reversals of the field are thus detectable as "stripes" centered on mid-ocean ridges where the sea floor is spreading, while the stability of the geomagnetic poles between reversals has allowed paleomagnetists to track the past motion of continents. Reversals also provide the basis for magnetostratigraphy, a way of dating rocks and sediments.[9] The field also magnetizes the crust, and magnetic anomalies can be used to search for deposits of metal ores.[10]

text: Humans have used compasses for direction finding since the 11th century A.D. and for navigation since the 12th century.[11] Although the magnetic declination does shift with time, this wandering is slow enough that a simple compass remains useful for navigation. Using magnetoception various other organisms, ranging from some types of bacteria to pigeons, use the Earth's magnetic field for orientation and navigation.

text: Main characteristics[edit]

text: Description[edit]

text: At any location, the Earth's magnetic field can be represented by a three-dimensional vector. A typical procedure for measuring its direction is to use a compass to determine the direction of magnetic North. Its angle relative to true North is the declination (D) or variation. Facing magnetic North, the angle the field makes with the horizontal is the inclination (I) or magnetic dip. The intensity (F) of the field is proportional to the force it exerts on a magnet. Another common representation is in X (North), Y (East) and Z (Down) coordinates.[12]

text: Intensity[edit]

text: The intensity of the field is often measured in gauss (G), but is generally reported in nanoteslas (nT), with 1 G = 100,000 nT. A nanotesla is also referred to as a gamma (γ).[13] The tesla is the SI unit of the Magnetic field, B. The Earth's field ranges between approximately 25,000 and 65,000 nT (0.25–0.65 G). By comparison, a strong refrigerator magnet has a field of about 10,000,000 nanoteslas (100 G).[14]

text: A map of intensity contours is called an isodynamic chart. As the World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs in the South Atlantic Anomaly over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.[15]

text: Inclination[edit]

text: The inclination is given by an angle that can assume values between -90° (up) to 90° (down). In the northern hemisphere, the field points downwards. It is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal (0°) at the magnetic equator. It continues to rotate upwards until it is straight up at the South Magnetic Pole. Inclination can be measured with a dip circle.

text: An isoclinic chart (map of inclination contours) for the Earth's magnetic field is shown below.

text: Declination[edit]

text: Declination is positive for an eastward deviation of the field relative to true north. It can be estimated by comparing the magnetic north/south heading on a compass with the direction of a celestial pole. Maps typically include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination).

text: Geographical variation[edit]

text: Components of the Earth's magnetic field at the surface from the World Magnetic Model for 2015.[15]

text:
Intensity

Inclination

Declination

tag: ul

text: Dipolar approximation[edit]

text: Near the surface of the Earth, its magnetic field can be closely approximated by the field of a magnetic dipole positioned at the center of the Earth and tilted at an angle of about 11° with respect to the rotational axis of the Earth.[13] The dipole is roughly equivalent to a powerful bar magnet, with its south pole pointing towards the geomagnetic North Pole.[16] This may seem surprising, but the north pole of a magnet is so defined because, if allowed to rotate freely, it points roughly northward (in the geographic sense). Since the north pole of a magnet attracts the south poles of other magnets and repels the north poles, it must be attracted to the south pole of Earth's magnet. The dipolar field accounts for 80–90% of the field in most locations.[12]

text: Magnetic poles[edit]

text: The positions of the magnetic poles can be defined in at least two ways: locally or globally.[17]

text: One way to define a pole is as a point where the magnetic field is vertical.[18] This can be determined by measuring the inclination, as described above. The inclination of the Earth's field is 90° (downwards) at the North Magnetic Pole and -90° (upwards) at the South Magnetic Pole. The two poles wander independently of each other and are not directly opposite each other on the globe. They can migrate rapidly: movements of up to 40 kilometres (25 mi) per year have been observed for the North Magnetic Pole. Over the last 180 years, the North Magnetic Pole has been migrating northwestward, from Cape Adelaide in the Boothia Peninsula in 1831 to 600 kilometres (370 mi) from Resolute Bay in 2001.[19] The magnetic equator is the line where the inclination is zero (the magnetic field is horizontal).

text: The global definition of the Earth's field is based on a mathematical model. If a line is drawn through the center of the Earth, parallel to the moment of the best-fitting magnetic dipole, the two positions where it intersects the Earth's surface are called the North and South geomagnetic poles. If the Earth's magnetic field were perfectly dipolar, the geomagnetic poles and magnetic dip poles would coincide and compasses would point towards them. However, the Earth's field has a significant non-dipolar contribution, so the poles do not coincide and compasses do not generally point at either.

text: Magnetosphere[edit]

text: Earth's magnetic field, predominantly dipolar at its surface, is distorted further out by the solar wind. This is a stream of charged particles leaving the Sun's corona and accelerating to a speed of 200 to 1000 kilometres per second. They carry with them a magnetic field, the interplanetary magnetic field (IMF).[20]

text: The solar wind exerts a pressure, and if it could reach Earth's atmosphere it would erode it. However, it is kept away by the pressure of the Earth's magnetic field. The magnetopause, the area where the pressures balance, is the boundary of the magnetosphere. Despite its name, the magnetosphere is asymmetric, with the sunward side being about 10 Earth radii out but the other side stretching out in a magnetotail that extends beyond 200 Earth radii.[21] Sunward of the magnetopause is the bow shock, the area where the solar wind slows abruptly.[20]

text: Inside the magnetosphere is the plasmasphere, a donut-shaped region containing low-energy charged particles, or plasma. This region begins at a height of 60 km, extends up to 3 or 4 Earth radii, and includes the ionosphere. This region rotates with the Earth.[21] There are also two concentric tire-shaped regions, called the Van Allen radiation belts, with high-energy ions (energies from 0.1 to 10 million electron volts (MeV)). The inner belt is 1–2 Earth radii out while the outer belt is at 4–7 Earth radii. The plasmasphere and Van Allen belts have partial overlap, with the extent of overlap varying greatly with solar activity.[22]

text: As well as deflecting the solar wind, the Earth's magnetic field deflects cosmic rays, high-energy charged particles that are mostly from outside the Solar system. (Many cosmic rays are kept out of the Solar system by the Sun's magnetosphere, or heliosphere.[23]) By contrast, astronauts on the Moon risk exposure to radiation. Anyone who had been on the Moon's surface during a particularly violent solar eruption in 2005 would have received a lethal dose.[20]

text: Some of the charged particles do get into the magnetosphere. These spiral around field lines, bouncing back and forth between the poles several times per second. In addition, positive ions slowly drift westward and negative ions drift eastward, giving rise to a ring current. This current reduces the magnetic field at the Earth's surface.[20] Particles that penetrate the ionosphere and collide with the atoms there give rise to the lights of the aurorae and also emit X-rays.[21]

text: The varying conditions in the magnetosphere, known as space weather, are largely driven by solar activity. If the solar wind is weak, the magnetosphere expands; while if it is strong, it compresses the magnetosphere and more of it gets in. Periods of particularly intense activity, called geomagnetic storms, can occur when a coronal mass ejection erupts above the Sun and sends a shock wave through the Solar System. Such a wave can take just two days to reach the Earth. Geomagnetic storms can cause a lot of disruption; the "Halloween" storm of 2003 damaged more than a third of NASA's satellites. The largest documented storm occurred in 1859. It induced currents strong enough to short out telegraph lines, and aurorae were reported as far south as Hawaii.[20][24]

text: Time dependence[edit]

text: Short-term variations[edit]

text: The geomagnetic field changes on time scales from milliseconds to millions of years. Shorter time scales mostly arise from currents in the ionosphere (ionospheric dynamo region) and magnetosphere, and some changes can be traced to geomagnetic storms or daily variations in currents. Changes over time scales of a year or more mostly reflect changes in the Earth's interior, particularly the iron-rich core.[12]

text: Frequently, the Earth's magnetosphere is hit by solar flares causing geomagnetic storms, provoking displays of aurorae. The short-term instability of the magnetic field is measured with the K-index.[25]

text: Data from THEMIS show that the magnetic field, which interacts with the solar wind, is reduced when the magnetic orientation is aligned between Sun and Earth – opposite to the previous hypothesis. During forthcoming solar storms, this could result in blackouts and disruptions in artificial satellites.[26]

text: Secular variation[edit]

text: Changes in Earth's magnetic field on a time scale of a year or more are referred to as secular variation. Over hundreds of years, magnetic declination is observed to vary over tens of degrees.[12] A movie on the right shows how global declinations have changed over the last few centuries.[27]

text: The direction and intensity of the dipole change over time. Over the last two centuries the dipole strength has been decreasing at a rate of about 6.3% per century.[12] At this rate of decrease, the field would be negligible in about 1600 years.[28] However, this strength is about average for the last 7 thousand years, and the current rate of change is not unusual.[29]

text: A prominent feature in the non-dipolar part of the secular variation is a westward drift at a rate of about 0.2 degrees per year.[28] This drift is not the same everywhere and has varied over time. The globally averaged drift has been westward since about 1400 AD but eastward between about 1000 AD and 1400 AD.[30]

text: Changes that predate magnetic observatories are recorded in archaeological and geological materials. Such changes are referred to as paleomagnetic secular variation or paleosecular variation (PSV). The records typically include long periods of small change with occasional large changes reflecting geomagnetic excursions and reversals.[31]

text: Magnetic field reversals[edit]

text: Although generally Earth's field is approximately dipolar, with an axis that is nearly aligned with the rotational axis, occasionally the North and South geomagnetic poles trade places. Evidence for these geomagnetic reversals can be found in basalts, sediment cores taken from the ocean floors, and seafloor magnetic anomalies.[32] Reversals occur nearly randomly in time, with intervals between reversals ranging from less than 0.1 million years to as much as 50 million years. The most recent geomagnetic reversal, called the Brunhes–Matuyama reversal, occurred about 780,000 years ago.[19][33] A related phenomenon, a geomagnetic excursion, amounts to an incomplete reversal, with no change in polarity.[34][35] The Laschamp event is an example of an excursion, it having occurred during the last ice age (41,000 years ago).

text: The past magnetic field is recorded mostly by strongly magnetic minerals, particularly iron oxides such as magnetite, that can carry a permanent magnetic moment. This remanent magnetization, or remanence, can be acquired in more than one way. In lava flows, the direction of the field is "frozen" in small minerals as they cool, giving rise to a thermoremanent magnetization. In sediments, the orientation of magnetic particles acquires a slight bias towards the magnetic field as they are deposited on an ocean floor or lake bottom. This is called detrital remanent magnetization.[8]

text: Thermoremanent magnetization is the main source of the magnetic anomalies around ocean ridges. As the seafloor spreads, magma wells up from the mantle, cools to form new basaltic crust on both sides of the ridge, and is carried away from it by seafloor spreading. As it cools, it records the direction of the Earth's field. When the Earth's field reverses, new basalt records the reversed direction. The result is a series of stripes that are symmetric about the ridge. A ship towing a magnetometer on the surface of the ocean can detect these stripes and infer the age of the ocean floor below. This provides information on the rate at which seafloor has spread in the past.[8]

text: Radiometric dating of lava flows has been used to establish a geomagnetic polarity time scale, part of which is shown in the image. This forms the basis of magnetostratigraphy, a geophysical correlation technique that can be used to date both sedimentary and volcanic sequences as well as the seafloor magnetic anomalies.[8]

text: Studies of lava flows on Steens Mountain, Oregon, indicate that the magnetic field could have shifted at a rate of up to 6 degrees per day at some time in Earth's history, which significantly challenges the popular understanding of how the Earth's magnetic field works.[36] This finding was later attributed to unusual rock magnetic properties of the lava flow under study, not rapid field change, by one of the original authors of the 1995 study.[37]

text: Temporary dipole tilt variations that take the dipole axis across the equator and then back to the original polarity are known as excursions.[35]

text: Earliest appearance[edit]

text: Paleomagnetic studies of Paleoarchean lava in Australia and conglomerate in South Africa have concluded that the magnetic field has been present since at least about 3,450 million years ago.[38][39][40]

text: Future[edit]

text: At present, the overall geomagnetic field is becoming weaker; the present strong deterioration corresponds to a 10–15% decline over the last 150 years and has accelerated in the past several years; geomagnetic intensity has declined almost continuously from a maximum 35% above the modern value achieved approximately 2,000 years ago. The rate of decrease and the current strength are within the normal range of variation, as shown by the record of past magnetic fields recorded in rocks.

text: The nature of Earth's magnetic field is one of heteroscedastic fluctuation. An instantaneous measurement of it, or several measurements of it across the span of decades or centuries, are not sufficient to extrapolate an overall trend in the field strength. It has gone up and down in the past for unknown reasons. Also, noting the local intensity of the dipole field (or its fluctuation) is insufficient to characterize Earth's magnetic field as a whole, as it is not strictly a dipole field. The dipole component of Earth's field can diminish even while the total magnetic field remains the same or increases.

text: The Earth's magnetic north pole is drifting from northern Canada towards Siberia with a presently accelerating rate—10 kilometres (6.2 mi) per year at the beginning of the 20th century, up to 40 kilometres (25 mi) per year in 2003,[19] and since then has only accelerated.[41]

text: Physical origin[edit]

text: The Earth's magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core. However the process is complex, and computer models that reproduce some of its features have only been developed in the last few decades.

text: Earth's core and the geodynamo[edit]

text: The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids.[43] The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km). It is divided into a solid inner core, with a radius of 1220 km, and a liquid outer core.[44] The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about 6,000 K (5,730 °C; 10,340 °F), to the core-mantle boundary, which is about 3,800 K (3,530 °C; 6,380 °F).[45] The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core.[46]

text: The mechanism by which the Earth generates a magnetic field is known as a dynamo.[43] The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force).[47] These effects can be combined in a partial differential equation for the magnetic field called the magnetic induction equation:

text: ...where u is the velocity of the fluid; B is the magnetic B-field; and η=1/σμ is the magnetic diffusivity, which is inversely proportional to the product of the electrical conductivity σ and the permeability μ .[48] The term ∂B/∂t is the time derivative of the field; ∇2 is the Laplace operator and ∇× is the curl operator.

text: The first term on the right hand side of the induction equation is a diffusion term. In a stationary fluid, the magnetic field declines and any concentrations of field spread out. If the Earth's dynamo shut off, the dipole part would disappear in a few tens of thousands of years.[48]

text:
In a perfect conductor (

σ
=
∞

{\displaystyle \sigma =\infty \;}

), there would be no diffusion. By Lenz's law, any change in the magnetic field would be immediately opposed by currents, so the flux through a given volume of fluid could not change. As the fluid moved, the magnetic field would go with it. The theorem describing this effect is called the frozen-in-field theorem. Even in a fluid with a finite conductivity, new field is generated by stretching field lines as the fluid moves in ways that deform it. This process could go on generating new field indefinitely, were it not that as the magnetic field increases in strength, it resists fluid motion.[48]

text: The motion of the fluid is sustained by convection, motion driven by buoyancy. The temperature increases towards the center of the Earth, and the higher temperature of the fluid lower down makes it buoyant. This buoyancy is enhanced by chemical separation: As the core cools, some of the molten iron solidifies and is plated to the inner core. In the process, lighter elements are left behind in the fluid, making it lighter. This is called compositional convection. A Coriolis effect, caused by the overall planetary rotation, tends to organize the flow into rolls aligned along the north-south polar axis.[46][48]

text: A dynamo can amplify a magnetic field, but it needs a "seed" field to get it started.[48] For the Earth, this could have been an external magnetic field. Early in its history the Sun went through a T-Tauri phase in which the solar wind would have had a magnetic field orders of magnitude larger than the present solar wind.[49] However, much of the field may have been screened out by the Earth's mantle. An alternative source is currents in the core-mantle boundary driven by chemical reactions or variations in thermal or electric conductivity. Such effects may still provide a small bias that are part of the boundary conditions for the geodynamo.[50]

text: The average magnetic field in the Earth's outer core was calculated to be 25 gauss, 50 times stronger than the field at the surface.[51]

text: Numerical models[edit]

text: Simulating the geodynamo requires numerically solving a set of nonlinear partial differential equations for the magnetohydrodynamics (MHD) of the Earth's interior. Simulation of the MHD equations is performed on a 3D grid of points and the fineness of the grid, which in part determines the realism of the solutions, is limited mainly by computer power. For decades, theorists were confined to creating kinematic dynamo computer models in which the fluid motion is chosen in advance and the effect on the magnetic field calculated. Kinematic dynamo theory was mainly a matter of trying different flow geometries and testing whether such geometries could sustain a dynamo.[52]

text: The first self-consistent dynamo models, ones that determine both the fluid motions and the magnetic field, were developed by two groups in 1995, one in Japan[53] and one in the United States.[1][54] The latter received attention because it successfully reproduced some of the characteristics of the Earth's field, including geomagnetic reversals.[52]

text: Currents in the ionosphere and magnetosphere[edit]

text: Electric currents induced in the ionosphere generate magnetic fields (ionospheric dynamo region). Such a field is always generated near where the atmosphere is closest to the Sun, causing daily alterations that can deflect surface magnetic fields by as much as one degree. Typical daily variations of field strength are about 25 nanoteslas (nT) (one part in 2000), with variations over a few seconds of typically around 1 nT (one part in 50,000).[55]

text: Measurement and analysis[edit]

text: Detection[edit]

text: The Earth's magnetic field strength was measured by Carl Friedrich Gauss in 1832[56] and has been repeatedly measured since then, showing a relative decay of about 10% over the last 150 years.[57] The Magsat satellite and later satellites have used 3-axis vector magnetometers to probe the 3-D structure of the Earth's magnetic field. The later Ørsted satellite allowed a comparison indicating a dynamic geodynamo in action that appears to be giving rise to an alternate pole under the Atlantic Ocean west of S. Africa.[58]

text: Governments sometimes operate units that specialize in measurement of the Earth's magnetic field. These are geomagnetic observatories, typically part of a national Geological survey, for example the British Geological Survey's Eskdalemuir Observatory. Such observatories can measure and forecast magnetic conditions such as magnetic storms that sometimes affect communications, electric power, and other human activities.

text: The International Real-time Magnetic Observatory Network, with over 100 interlinked geomagnetic observatories around the world has been recording the earths magnetic field since 1991.

text: The military determines local geomagnetic field characteristics, in order to detect anomalies in the natural background that might be caused by a significant metallic object such as a submerged submarine. Typically, these magnetic anomaly detectors are flown in aircraft like the UK's Nimrod or towed as an instrument or an array of instruments from surface ships.

text: Commercially, geophysical prospecting companies also use magnetic detectors to identify naturally occurring anomalies from ore bodies, such as the Kursk Magnetic Anomaly.

text: Crustal magnetic anomalies[edit]

text: Magnetometers detect minute deviations in the Earth's magnetic field caused by iron artifacts, kilns, some types of stone structures, and even ditches and middens in archaeological geophysics. Using magnetic instruments adapted from airborne magnetic anomaly detectors developed during World War II to detect submarines,[60] the magnetic variations across the ocean floor have been mapped. Basalt — the iron-rich, volcanic rock making up the ocean floor[61] — contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. The distortion was recognized by Icelandic mariners as early as the late 18th century.[62] More important, because the presence of magnetite gives the basalt measurable magnetic properties, these magnetic variations have provided another means to study the deep ocean floor. When newly formed rock cools, such magnetic materials record the Earth's magnetic field.[62]

text: Statistical models[edit]

text: Each measurement of the magnetic field is at a particular place and time. If an accurate estimate of the field at some other place and time is needed, the measurements must be converted to a model and the model used to make predictions.

text: Spherical harmonics[edit]

text: The most common way of analyzing the global variations in the Earth's magnetic field is to fit the measurements to a set of spherical harmonics. This was first done by Carl Friedrich Gauss.[63] Spherical harmonics are functions that oscillate over the surface of a sphere. They are the product of two functions, one that depends on latitude and one on longitude. The function of longitude is zero along zero or more great circles passing through the North and South Poles; the number of such nodal lines is the absolute value of the order m. The function of latitude is zero along zero or more latitude circles; this plus the order is equal to the degree ℓ. Each harmonic is equivalent to a particular arrangement of magnetic charges at the center of the Earth. A monopole is an isolated magnetic charge, which has never been observed. A dipole is equivalent to two opposing charges brought close together and a quadrupole to two dipoles brought together. A quadrupole field is shown in the lower figure on the right.[12]

text: Spherical harmonics can represent any scalar field (function of position) that satisfies certain properties. A magnetic field is a vector field, but if it is expressed in Cartesian components X, Y, Z, each component is the derivative of the same scalar function called the magnetic potential. Analyses of the Earth's magnetic field use a modified version of the usual spherical harmonics that differ by a multiplicative factor. A least-squares fit to the magnetic field measurements gives the Earth's field as the sum of spherical harmonics, each multiplied by the best-fitting Gauss coefficient gmℓ or hmℓ.[12]

text: The lowest-degree Gauss coefficient, g00, gives the contribution of an isolated magnetic charge, so it is zero. The next three coefficients – g10, g11, and h11 – determine the direction and magnitude of the dipole contribution. The best fitting dipole is tilted at an angle of about 10° with respect to the rotational axis, as described earlier.[12]

text: Radial dependence[edit]

text: Spherical harmonic analysis can be used to distinguish internal from external sources if measurements are available at more than one height (for example, ground observatories and satellites). In that case, each term with coefficient gmℓ or hmℓ can be split into two terms: one that decreases with radius as 1/rℓ+1 and one that increases with radius as rℓ. The increasing terms fit the external sources (currents in the ionosphere and magnetosphere). However, averaged over a few years the external contributions average to zero.[12]

text: The remaining terms predict that the potential of a dipole source (ℓ=1) drops off as 1/r2. The magnetic field, being a derivative of the potential, drops off as 1/r3. Quadrupole terms drop off as 1/r4, and higher order terms drop off increasingly rapidly with the radius. The radius of the outer core is about half of the radius of the Earth. If the field at the core-mantle boundary is fit to spherical harmonics, the dipole part is smaller by a factor of about 8 at the surface, the quadrupole part by a factor of 16, and so on. Thus, only the components with large wavelengths can be noticeable at the surface. From a variety of arguments, it is usually assumed that only terms up to degree 14 or less have their origin in the core. These have wavelengths of about 2,000 kilometres (1,200 mi) or less. Smaller features are attributed to crustal anomalies.[12]

text: Global models[edit]

text: The International Association of Geomagnetism and Aeronomy maintains a standard global field model called the International Geomagnetic Reference Field. It is updated every 5 years. The 11th-generation model, IGRF11, was developed using data from satellites (Ørsted, CHAMP and SAC-C) and a world network of geomagnetic observatories.[64] The spherical harmonic expansion was truncated at degree 10, with 120 coefficients, until 2000. Subsequent models are truncated at degree 13 (195 coefficients).[65]

text: Another global field model, called World Magnetic Model, is produced jointly by the United States National Centers for Environmental Information (formerly the National Geophysical Data Center) and the British Geological Survey. This model truncates at degree 12 (168 coefficients) with an approximate spatial resolution of 3,000 kilometers. It is the model used by the United States Department of Defense, the Ministry of Defence (United Kingdom), the United States Federal Aviation Administration (FAA), the North Atlantic Treaty Organization (NATO), and the International Hydrographic Office as well as in many civilian navigation systems.[66]

text: A third model, produced by the Goddard Space Flight Center (NASA and GSFC) and the Danish Space Research Institute, uses a "comprehensive modeling" approach that attempts to reconcile data with greatly varying temporal and spatial resolution from ground and satellite sources.[67]

text: For users with higher accuracy needs, the United States National Centers for Environmental Information developed the Enhanced Magnetic Model (EMM), which extends to degree and order 720 and resolves magnetic anomalies down to a wavelength of 56 kilometers. It was compiled from satellite, marine, aeromagnetic and ground magnetic surveys. The latest version, EMM2015, includes data from The European Space Agency's Swarm satellite mission.[68]

text: Biomagnetism[edit]

text: Animals including birds and turtles can detect the Earth's magnetic field, and use the field to navigate during migration.[69] Some researchers have found that cows and wild deer tend to align their bodies north-south while relaxing, but not when the animals are under high-voltage power lines, suggesting that magnetism is responsible.[70][71] Other researchers reported in 2011 that they could not replicate those findings using different Google Earth images.[72]

text: Researchers found out that very weak electromagnetic fields disrupt the magnetic compass used by European robins and other songbirds to navigate using the Earth's magnetic field. Neither power lines nor cellphone signals are to blame for the electromagnetic field effect on the birds, according to the new study published in the 8 May 2014 edition of the journal Nature. Instead, the culprits consist of frequencies between 2 kHz and 5 MHz, such as AM radio signals and ordinary electronic equipment that might be found in businesses or private homes.[73]