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Tuesday, March 3, 2015

Thor Heyerdahl



From Wikipedia, the free encyclopedia

Thor Heyerdahl
ThorHeyerdahl.jpg
Born (1914-10-06)October 6, 1914
Larvik, Norway
Died April 18, 2002(2002-04-18) (aged 87)
Colla Micheri, Italy
Nationality Norwegian
Fields Ethnography
Adventure
Alma mater University of Oslo
Doctoral advisor Kristine Bonnevie
Hjalmar Broch
Notable awards Mungo Park Medal (1950)

Thor Heyerdahl (Norwegian pronunciation: [tuːr hæiːərdɑːl]; October 6, 1914 – April 18, 2002) was a Norwegian adventurer and ethnographer with a background in zoology, botany, and geography. He became notable for his Kon-Tiki expedition in 1947, in which he sailed 8,000 km (5,000 mi) across the Pacific Ocean in a hand-built raft from South America to the Tuamotu Islands. The expedition was designed to demonstrate that ancient people could have made long sea voyages, creating contacts between separate cultures. This was linked to a diffusionist model of cultural development.
Heyerdahl subsequently made other voyages designed to demonstrate the possibility of contact between widely separated ancient people. He was appointed a government scholar in 1984.

In May 2011, the Thor Heyerdahl Archives were added to UNESCO's "Memory of the World" Register.[1] At the time, this list included 238 collections from all over the world.[2] The Heyerdahl Archives span the years 1937 to 2002 and include his photographic collection, diaries, private letters, expedition plans, articles, newspaper clippings, original book, and article manuscripts. The Heyerdahl Archives are administered by the Kon-Tiki Museum and the National Library of Norway in Oslo.

Youth and personal life

Heyerdahl was born in Larvik, Norway, the son of master brewer Thor Heyerdahl and his wife, Alison Lyng. As a young child, Heyerdahl showed a strong interest in zoology. He created a small museum in his childhood home, with a common adder (Vipera berus) as the main attraction. He studied zoology and geography at the faculty of biological science at the University of Oslo.[3] At the same time, he privately studied Polynesian culture and history, consulting what was then the world's largest private collection of books and papers on Polynesia, owned by Bjarne Kropelien, a wealthy wine merchant in Oslo. (This collection was later purchased by the University of Oslo Library from Kropelien's heirs and was attached to the Kon-Tiki Museum research department.) After seven terms and consultations with experts in Berlin, a project was developed and sponsored by Heyerdahl's zoology professors, Kristine Bonnevie and Hjalmar Broch. He was to visit some isolated Pacific island groups and study how the local animals had found their way there.

Just before sailing together to the Marquesas Islands in 1936, Heyerdahl married his first wife, Liv Coucheron-Torp (1916–1969), whom he had met shortly before enrolling at the university, and who had studied economics there. The couple had two sons; Thor Jr and Bjørn. The marriage ended in divorce.

After the Occupation of Norway by Nazi Germany he served with the Free Norwegian Forces from 1944, in the far north province of Finnmark.[4][5]

In 1949 Heyerdahl married Yvonne Dedekam-Simonsen (1924–2006). They had three daughters: Annette, Marian and Helene Elisabeth. They were divorced in 1969. Heyerdahl blamed their separation on his being away from home and differences in their ideas for bringing up children. In his autobiography, he concluded that he should take the entire blame for their separation.[6]

In 1991, Heyerdahl married Jacqueline Beer (born 1932) as his third wife. They lived in Tenerife, Canary Islands and were very actively involved with archaeological projects, especially in Túcume, Peru, and Azov until his death in 2002. He still had been hoping to undertake an archaeological project in Samoa before he died.[7]

Heyerdahl died on April 18, 2002, in Colla Micheri, Liguria, Italy, where he had gone to spend the Easter holidays with some of his closest family members. The Norwegian government gave him a state funeral in Oslo Cathedral on April 26, 2002. He is buried in the garden of the family home in Colla Micheri.[8]

Fatu Hiva

The events surrounding his stay on the Marquesas, most of the time on Fatu Hiva, were told first in his book På Jakt etter Paradiset (Hunt for Paradise) (1938), which was published in Norway but, following the outbreak of World War II, never translated and largely forgotten. Many years later, having achieved notability with other adventures and books on other subjects, Heyerdahl published a new account of this voyage under the title Fatu Hiva (London: Allen & Unwin, 1974). The story of his time on Fatu Hiva and his side trip to Hivaoa and Mohotani is also related in Green Was the Earth on the Seventh Day (Random House, 1996).

Kon-Tiki expedition

In 1947, Heyerdahl and five fellow adventurers sailed from Peru to the Tuamotus, French Polynesia, in a pae-pae raft they constructed from balsa wood and other native materials, and christened the Kon-Tiki. The Kon-Tiki expedition was inspired by old reports and drawings made by the Spanish Conquistadors of Inca rafts, and by native legends and archaeological evidence suggesting contact between South America and Polynesia. On August 7, 1947, after a 101-day, 4,300 nautical mile (4,948 miles or 7,964 km)[9] journey across the Pacific Ocean, the Kon-Tiki smashed into the reef at Raroia in the Tuamotu Islands. Heyerdahl, who had nearly drowned at least twice in childhood and did not take easily to water, said later that there were times in each of his raft voyages when he feared for his life.[10]
Kon-Tiki demonstrated that it was possible for a primitive raft to sail the Pacific with relative ease and safety, especially to the west (with the trade winds). The raft proved to be highly maneuverable, and fish congregated between the nine balsa logs in such numbers that ancient sailors could have possibly relied on fish for hydration in the absence of other sources of fresh water. Inspired by Kon-Tiki, other rafts have repeated the voyage. Heyerdahl's book about the expedition, The Kon-Tiki Expedition: By Raft Across the South Seas, has been translated into 70 languages.[11] The documentary film of the expedition, itself entitled Kon-Tiki, won an Academy Award in 1951. A dramatised version was released in 2012, also called Kon-Tiki, and was nominated for both the Best Foreign Language Oscar at the 85th Academy Awards[12] and a Golden Globe Award for Best Foreign Language Film at the 70th Golden Globe Awards.[13] It is the first time a Norwegian film has been nominated for both an Oscar and a Golden Globe.[14]

Anthropologists continue to believe, based on linguistic, physical, and genetic evidence, that Polynesia was settled from west to east, migration having begun from the Asian mainland. There are controversial indications, though, of some sort of South American/Polynesian contact, most notably in the fact that the South American sweet potato is served as a dietary staple throughout much of Polynesia. Blood samples taken in 1971 and 2008 from Easter Islanders without any European or other external descent were analysed in a 2011 study, which concluded that the evidence supported some aspects of Heyerdahl's hypothesis.[15][16][17] This result has been questioned because of the possibility of contamination by South Americans after European contact with the islands.[18] However, more recent DNA work (after Heyerdahl's death) contradicts the post-European-contact contamination hypothesis, finding the South American DNA sequences to be far older than that. [19] Heyerdahl had attempted to counter the linguistic argument with the analogy that, guessing the origin of African-Americans, he would prefer to believe that they came from Africa, judging from their skin colour, and not from England, judging from their speech.

Theory on Polynesian origins

Heyerdahl claimed that in Incan legend there was a sun-god named Con-Tici Viracocha who was the supreme head of the mythical fair-skinned people in Peru. The original name for Viracocha was Kon-Tiki or Illa-Tiki, which means Sun-Tiki or Fire-Tiki. Kon-Tiki was high priest and sun-king of these legendary "white men" who left enormous ruins on the shores of Lake Titicaca. The legend continues with the mysterious bearded white men being attacked by a chief named Cari who came from the Coquimbo Valley. They had a battle on an island in Lake Titicaca, and the fair race was massacred. However, Kon-Tiki and his closest companions managed to escape and later arrived on the Pacific coast. The legend ends with Kon-Tiki and his companions disappearing westward out to sea.

When the Spaniards came to Peru, Heyerdahl asserted, the Incas told them that the colossal monuments that stood deserted about the landscape were erected by a race of white gods who had lived there before the Incas themselves became rulers. The Incas described these "white gods" as wise, peaceful instructors who had originally come from the north in the "morning of time" and taught the Incas' primitive forefathers architecture as well as manners and customs. They were unlike other Native Americans in that they had "white skins and long beards" and were taller than the Incas. The Incas said that the "white gods" had then left as suddenly as they had come and fled westward across the Pacific. After they had left, the Incas themselves took over power in the country.

Heyerdahl said that when the Europeans first came to the Pacific islands, they were astonished that they found some of the natives to have relatively light skins and beards. There were whole families that had pale skin, hair varying in color from reddish to blonde. In contrast, most of the Polynesians had golden-brown skin, raven-black hair, and rather flat noses. Heyerdahl claimed that when Jakob Roggeveen first discovered Easter Island in 1722, he supposedly noticed that many of the natives were white-skinned. Heyerdahl claimed that these people could count their ancestors who were "white-skinned" right back to the time of Tiki and Hotu Matua, when they first came sailing across the sea "from a mountainous land in the east which was scorched by the sun." The ethnographic evidence for these claims is outlined in Heyerdahl's book Aku Aku: The Secret of Easter Island.

Heyerdahl proposed that Tiki's neolithic people colonized the then-uninhabited Polynesian islands as far north as Hawaii, as far south as New Zealand, as far east as Easter Island, and as far west as Samoa and Tonga around 500 AD. They supposedly sailed from Peru to the Polynesian islands on pae-paes—large rafts built from balsa logs, complete with sails and each with a small cottage. They built enormous stone statues carved in the image of human beings on Pitcairn, the Marquesas, and Easter Island that resembled those in Peru. They also built huge pyramids on Tahiti and Samoa with steps like those in Peru. But all over Polynesia, Heyerdahl found indications that Tiki's peaceable race had not been able to hold the islands alone for long. He found evidence that suggested that seagoing war canoes as large as Viking ships and lashed together two and two had brought Stone Age Northwest American Indians to Polynesia around 1100 AD, and they mingled with Tiki's people. The oral history of the people of Easter Island, at least as it was documented by Heyerdahl, is completely consistent with this theory, as is the archaeological record he examined (Heyerdahl 1958). In particular, Heyerdahl obtained a radiocarbon date of 400 AD for a charcoal fire located in the pit that was held by the people of Easter Island to have been used as an "oven" by the "Long Ears," which Heyerdahl's Rapa Nui sources, reciting oral tradition, identified as a white race which had ruled the island in the past (Heyerdahl 1958).

Heyerdahl further argued in his book American Indians in the Pacific that the current inhabitants of Polynesia migrated from an Asian source, but via an alternate route. He proposes that Polynesians travelled with the wind along the North Pacific current. These migrants then arrived in British Columbia. Heyerdahl called contemporary tribes of British Columbia, such as the Tlingit and Haida, descendants of these migrants. Heyerdahl claimed that cultural and physical similarities existed between these British Columbian tribes, Polynesians, and the Old World source. Heyerdahl's claims aside, however, there is no evidence that the Tlingit, Haida or other British Columbian tribes have an affinity with Polynesians.

Heyerdahl's theory of Polynesian origins has not gained acceptance among anthropologists.[20][21][22] Physical and cultural evidence had long suggested that Polynesia was settled from west to east, migration having begun from the Asian mainland, not South America. In the late 1990s, genetic testing found that the mitochondrial DNA of the Polynesians is more similar to people from southeast Asia than to people from South America, showing that their ancestors most likely came from Asia.[23]

A recent study by Norwegian researcher Erik Thorsby suggests that there is some merit to Heyerdahl's ideas and that while Polynesia was colonized from Asia, some contact with South America also existed.[24][25] Some critics suggest, however, that Thorsby's research is inconclusive because his data may have been influenced by recent population contact.[26] However, more recent work indicates that the South American component of Easter Island people's genomes predates European contact: a team including Anna-Sapfo Malaspinas (from the Natural History Museum of Denmark) analysed the genomes of 27 native Rapanui people and found that their DNA was on average 76 per cent Polynesian, eight per cent Native American and 16 per cent European. Analysis showed that: "although the European lineage could be explained by contact with white Europeans after the island was “discovered” in 1722 by Dutch sailors, the South American component was much older, dating to between about 1280 and 1495, soon after the island was first colonised by Polynesians in around 1200." Together with ancient skulls found in Brazil - with solely Polynesian DNA, this does suggest some pre-European-contact travel to and from South America from Polynesia.[27]

Anthropologist Robert Carl Suggs included a chapter titled "The Kon-Tiki Myth" in his book on Polynesia, concluding that "The Kon-Tiki theory is about as plausible as the tales of Atlantis, Mu, and 'Children of the Sun.' Like most such theories it makes exciting light reading, but as an example of scientific method it fares quite poorly."[28]

Anthropologist and National Geographic Explorer-in-Residence Wade Davis also criticised Heyerdahl's theory in his book The Wayfinders, which explores the history of Polynesia. Davis says that Heyerdahl "ignored the overwhelming body of linguistic, ethnographic, and ethnobotanical evidence, augmented today by genetic and archaeological data, indicating that he was patently wrong."[29]

Expedition to Rapa Nui (Easter Island)

In 1955–1956, Heyerdahl organized the Norwegian Archaeological Expedition to Rapa Nui (Easter Island). The expedition's scientific staff included Arne Skjølsvold, Carlyle Smith, Edwin Ferdon, Gonzalo Figueroa[30] and William Mulloy. Heyerdahl and the professional archaeologists who traveled with him spent several months on Rapa Nui investigating several important archaeological sites. Highlights of the project include experiments in the carving, transport and erection of the notable moai, as well as excavations at such prominent sites as Orongo and Poike. The expedition published two large volumes of scientific reports (Reports of the Norwegian Archaeological Expedition to Easter Island and the East Pacific) and Heyerdahl later added a third (The Art of Easter Island). Heyerdahl's popular book on the subject, Aku-Aku was another international best-seller.

In Easter Island: The Mystery Solved (Random House, 1989), Heyerdahl offered a more detailed theory of the island's history. Based on native testimony and archaeological research, he claimed the island was originally colonized by Hanau eepe ("Long Ears"), from South America, and that Polynesians Hanau momoko ("Short Ears") arrived only in the mid-16th century; they may have come independently or perhaps were imported as workers. According to Heyerdahl, something happened between Admiral Roggeveen's discovery of the island in 1722 and James Cook's visit in 1774; while Roggeveen encountered white, Indian, and Polynesian people living in relative harmony and prosperity, Cook encountered a much smaller population consisting mainly of Polynesians and living in privation.

Heyerdahl notes the oral tradition of an uprising of "Short Ears" against the ruling "Long Ears." The "Long Ears" dug a defensive moat on the eastern end of the island and filled it with kindling. During the uprising, Heyerdahl claimed, the "Long Ears" ignited their moat and retreated behind it, but the "Short Ears" found a way around it, came up from behind, and pushed all but two of the "Long Ears" into the fire. This moat was found by the Norwegian expedition and it was partly cut down into the rock. Layers of fire was revealed but no fragments of bodies. As for the origin of the people of Easter Island today (2013) DNA-tests have shown a total agreement with people from the Pacific and no connection to South America. If the story that all (almost) long-ears were killed in a civil war, this is what to be expected if their blood-line was totally destroyed. Recent (2006?) test has shown traces to South America from some proteins, but whether this is inherited from a person coming in later times is hard to know.

Boats Ra and Ra II


Ra II in the Kon-Tiki Museum

In 1969 and 1970, Heyerdahl built two boats from papyrus and attempted to cross the Atlantic Ocean from Morocco in Africa. Based on drawings and models from ancient Egypt, the first boat, named Ra (after the Egyptian Sun god), was constructed by boat builders from Lake Chad using papyrus reed obtained from Lake Tana in Ethiopia and launched into the Atlantic Ocean from the coast of Morocco. The Ra crew included Thor Heyerdahl (Norway), Norman Baker (USA), Carlo Mauri (Italy), Yuri Senkevich (USSR), Santiago Genoves (Mexico), Georges Sourial (Egypt) and Abdullah Djibrine (Chad). Only Heyerdahl and Baker had sailing and navigation experiences. After a number of weeks, Ra took on water after its crew made modifications to the vessel that caused it to sag and break apart after sailing more than 6440 km (4000 miles). The crew was forced to abandon Ra some hundred miles before Caribbean islands and was saved by a yacht.

The following year, 1970, another similar vessel, Ra II, was built of papyrus by Demetrio, Juan and Jose Limachi from Lake Titicaca in Bolivia and likewise set sail across the Atlantic from Morocco, this time with great success. The crew was mostly the same; only Djibrine had been replaced by Kei Ohara from Japan and Madani Ait Ouhanni from Morocco. The boat reached Barbados, thus demonstrating that mariners could have dealt with trans-Atlantic voyages by sailing with the Canary Current.[31]

The book The Ra Expeditions and the film documentary Ra (1972) were made about the voyages. Apart from the primary aspects of the expedition, Heyerdahl deliberately selected a crew representing a great diversity in race, nationality, religion and political viewpoint in order to demonstrate that at least on their own little floating island, people could cooperate and live peacefully. Additionally, the expedition took samples of marine pollution and presented their report to the United Nations.[32]

Tigris


Model of the Tigris at the Pyramids of Güímar, Tenerife.

Heyerdahl built yet another reed boat, Tigris, which was intended to demonstrate that trade and migration could have linked Mesopotamia with the Indus Valley Civilization in what is now Pakistan. Tigris was built in Iraq and sailed with its international crew through the Persian Gulf to Pakistan and made its way into the Red Sea. After about five months at sea and still remaining seaworthy, the Tigris was deliberately burnt in Djibouti, on April 3, 1978, as a protest against the wars raging on every side in the Red Sea and Horn of Africa. In his Open Letter to the UN Secretary-General Kurt Waldheim, Heyerdahl explained his reasons:[33]
Today we burn our proud ship ... to protest against inhuman elements in the world of 1978 ... Now we are forced to stop at the entrance to the Red Sea. Surrounded by military airplanes and warships from the world's most civilized and developed nations, we have been denied permission by friendly governments, for reasons of security, to land anywhere, but in the tiny, and still neutral, Republic of Djibouti. Elsewhere around us, brothers and neighbors are engaged in homicide with means made available to them by those who lead humanity on our joint road into the third millennium.
To the innocent masses in all industrialized countries, we direct our appeal. We must wake up to the insane reality of our time ... We are all irresponsible, unless we demand from the responsible decision makers that modern armaments must no longer be made available to people whose former battle axes and swords our ancestors condemned.
Our planet is bigger than the reed bundles that have carried us across the seas, and yet small enough to run the same risks unless those of us still alive open our eyes and minds to the desperate need of intelligent collaboration to save ourselves and our common civilization from what we are about to convert into a sinking ship.
In the years that followed, Heyerdahl was often outspoken on issues of international peace and the environment. The Tigris was crewed by eleven men: Thor Heyerdahl (Norway), Norman Baker (USA), Carlo Mauri (Italy), Yuri Senkevich (USSR), Germán Carrasco (Mexico), Hans Petter Bohn (Norway), Rashad Nazar Salim (Iraq), Norris Brock (USA), Toru Suzuki (Japan), Detlef Zoltze (Germany), and Asbjørn Damhus (Denmark).

"The Search for Odin" in Azerbaijan and Russia

Heyerdahl made four visits to Azerbaijan in 1981,[34] 1994, 1999 and 2000.[35] Heyerdahl had long been fascinated with the rock carvings that date back to about 8th-7th millennia BCE at Gobustan (about 30 miles west of Baku). He was convinced that their artistic style closely resembles the carvings found in his native Norway. The ship designs, in particular, were regarded by Heyerdahl as similar and drawn with a simple sickle–shaped lines, representing the base of the boat, with vertical lines on deck, illustrating crew or, perhaps, raised oars.

Based on this and other published documentation, Heyerdahl proposed that Azerbaijan was the site of an ancient advanced civilization. He believed natives migrated north through waterways to present-day Scandinavia using ingeniously constructed vessels made of skins that could be folded like cloth. When voyagers traveled upstream, they conveniently folded their skin boats and transported them via pack animals.

On Heyerdahl's visit to Baku in 1999, he lectured at the Academy of Sciences about the history of ancient Nordic Kings. He spoke of a notation made by Snorri Sturluson, a 13th-century historian-mythographer in Ynglinga Saga which relates that "Odin (a Scandinavian god who was one of the kings) came to the North with his people from a country called Aser."[36] (see also House of Ynglings and Mythological kings of Sweden). Heyerdahl accepted Snorri's story as literal truth, and believed that a chieftain led his people in a migration from the east, westward and northward through Saxony, to Fyn in Denmark, and eventually settling in Sweden. Heyerdahl claimed that the geographic location of the mythic Aser or Æsir matched the region of contemporary Azerbaijan - "east of the Caucasus mountains and the Black Sea". "We are no longer talking about mythology," Heyerdahl said, "but of the realities of geography and history. Azerbaijanis should be proud of their ancient culture. It is just as rich and ancient as that of China and Mesopotamia."

One of the last projects of his life, Jakten på Odin, 'The Search for Odin', was a sudden revision of his Odin hypothesis, in furtherance of which he initiated 2001–2002 excavations in Azov, Russia, near the Sea of Azov at the northeast of the Black Sea.[37] He searched for the remains of a civilization to match the account of Odin in Snorri Sturlusson, quite a bit north of his original target of Azerbaijan on the Caspian Sea only two years earlier. This project generated harsh criticism and accusations of pseudo-science from historians, archaeologists and linguists in Norway, who accused Heyerdahl of selective use of sources, and a basic lack of scientific methodology in his work.[38][39]

His central claims were based on similarities of names in Norse mythology and geographic names in the Black Sea region, e.g. Azov and Æsir, Udi and Odin, Tyr and Turkey. Philologists and historians reject these parallels as mere coincidences, and also anachronisms, for instance the city of Azov did not have that name until over 1000 years after Heyerdahl claims the Æsir dwelt there. The controversy surrounding the Search for Odin project was in many ways typical of the relationship between Heyerdahl and the academic community. His theories rarely won any scientific acceptance, whereas Heyerdahl himself rejected all scientific criticism and concentrated on publishing his theories in popular books aimed at the general public[citation needed].

As of 2012, Heyerdahl's Odin hypothesis has yet to be validated by any historian, archaeologist or linguist.

Other projects

Heyerdahl also investigated the mounds found on the Maldive Islands in the Indian Ocean. There, he found sun-oriented foundations and courtyards, as well as statues with elongated earlobes. Heyerdahl believed that these finds fit with his theory of a seafaring civilization which originated in what is now Sri Lanka, colonized the Maldives, and influenced or founded the cultures of ancient South America and Easter Island. His discoveries are detailed in his book The Maldive Mystery.

In 1991 he studied the Pyramids of Güímar on Tenerife and declared that they were not random stone heaps but pyramids. Based on the discovery made by the astrophysicists Aparicio, Belmonte and Esteban, from the Instituto de Astrofísica de Canarias that the "pyramids" were astronomically oriented and being convinced that they were of ancient origin, he claimed that the ancient people who built them were most likely sun worshipers. Heyerdahl advanced a theory according to which the Canaries had been bases of ancient shipping between America and the Mediterranean.

Heyerdahl was also an active figure in Green politics. He was the recipient of numerous medals and awards. He also received 11 honorary doctorates from universities in the Americas and Europe.

Death


Thor Heyerdahl's tomb at Colla Micheri

In subsequent years, Heyerdahl was involved with many other expeditions and archaeological projects. He remained best known for his boat-building, and for his emphasis on cultural diffusionism. He died, aged 87, from a brain tumor. After receiving the diagnosis he prepared for dying by refusing to eat or take medication.[40] The Norwegian government granted Heyerdahl the honor of a state funeral in the Oslo Cathedral on April 26, 2002. His cremated remains lie in the garden of his family's home in Colla Micheri.

Legacy


Quotation on borders next to the KonTiki museum in Oslo
  • Heyerdahl's expeditions were spectacular and caught the public imagination. Although much of his work remains unaccepted within the scientific community, Heyerdahl increased public interest in ancient history and anthropology. He also showed that long distance ocean voyages were possible with ancient designs. As such, he was a major practitioner of experimental archaeology. He introduced readers of all ages to the fields of archaeology and ethnology.
  • Heyerdahl's grandson, Olav Heyerdahl, retraced his grandfather's Kon-Tiki voyage in 2006 as part of a six-member crew. The voyage, organized by Torgeir Higraff and called the Tangaroa Expedition,[41] was intended as a tribute to Heyerdahl, an effort to better understand navigation via centerboards ("guara[42]") as well as a means to monitor the Pacific Ocean's environment.
  • A book about the Tangaroa Expedition[43] by Torgeir Higraff was published in 2007. The book has numerous photos from the Kon-Tiki voyage 60 years earlier and is illustrated with photographs by Tangaroa crew member Anders Berg (Oslo: Bazar Forlag, 2007). "Tangaroa Expedition" has also been produced as a documentary DVD in English, Norwegian, Swedish and Spanish.
  • The Thor Heyerdahl Institute was established in 2000. Heyerdahl himself agreed to the founding of the institute and it aims to promote and continue to develop Heyerdahl's ideas and principles. The institute is located in Heyerdahl's birth town in Larvik, Norway.
  • In Larvik, the birthplace of Heyerdahl, the municipality began a project in 2007 to attract more visitors. Since then, they have purchased and renovated Heyerdahl's childhood home, arranged a yearly raft regatta in his honour at the end of summer and begun to develop a Heyerdahl centre.[44]
  • Paul Theroux, in his book The Happy Isles of Oceania, criticizes Heyerdahl for trying to link the culture of Polynesian islands with the Peruvian culture. However, recent scientific investigation that compares the DNA of some of the Polynesian islands with natives from Peru suggests that there is some merit to Heyerdahl's ideas and that while Polynesia was colonized from Asia, some contact with South America also existed.[24][25]
  • Dubai College, an independent British school in Dubai, named one of the school's houses Heyerdahl. Other school house names for Dubai College include Barbarossa, Chichester and Cousteau, all surnames of famous explorers.

Decorations and honorary degrees


Bust of Thor Heyerdahl. Güímar, Tenerife.

Asteroid 2473 Heyerdahl is named after him, as are HNoMS Thor Heyerdahl, a Norwegian Nansen class frigate, along with MS Thor Heyerdahl (now renamed MS Vana Tallinn) and Thor Heyerdahl, a German three-masted sail training vessel originally owned by a participant of the Tigris expedition. Thor Heyerdahl Upper Secondary School in Larvik, the town of his birth, is also named after him.
Heyerdahl's numerous awards and honors include the following:

Governmental and state honors

Academic honors

Honorary degrees

Books

  • På Jakt efter Paradiset (Hunt for Paradise), 1938; Fatu-Hiva: Back to Nature (changed title in English in 1974).
  • The Kon-Tiki Expedition: By Raft Across the South Seas (Kon-Tiki ekspedisjonen, also known as Kon-Tiki: Across the Pacific in a Raft), 1948.
  • American Indians in the Pacific: The Theory Behind the Kon-Tiki Expedition (Chicago: Rand McNally, 1952), 821 pages.
  • Aku-Aku: The Secret of Easter Island ISBN 0-14-001454-3
  • Sea Routes to Polynesia: American Indians and Early Asiatics in the Pacific (Chicago: Rand McNally, 1968), 232 pages.
  • The Ra Expeditions ISBN 0-14-003462-5.
  • Early Man and the Ocean: The Beginning of Navigation and Seaborn Civilizations
  • The Tigris Expedition: In Search of Our Beginnings
  • The Maldive Mystery
  • Green Was the Earth on the Seventh Day: Memories and Journeys of a Lifetime
  • Pyramids of Tucume: The Quest for Peru's Forgotten City
  • In the Footsteps of Adam: A Memoir (the official edition is Abacus, 2001, translated by Ingrid Christophersen) ISBN 0-349-11273-8
  • Ingen grenser (No Boundaries, Norwegian only), 1999[52]
  • Jakten på Odin (Theories about Odin, Norwegian only), 2001
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Friends of Science ask NASA to Revise 97% Consensus Statements on Climate Change and Global Warming


Friends of Science today sent a letter to Charles Bolden, Chief Administrator, asking NASA to revise the consensus claim on the climate change section of NASA’s web-site which the Friends say is misleading. Friends of Science state that their research reveals there has never been a valid consensus study of scientists on climate change and the three polls cited by NASA in fact show that only 1-3% of some climate scientists agree with the Intergovernmental Panel on Climate Change definition of Catastrophic Anthropogenic Global Warming.

Doran & Zimmerman (2009) only assessed 79 scientists out of 3,146 respondents, asking two opinion questions about what should be an empirical, scientific topic 
 
Calgary, Alberta (PRWEB) March 03, 2015 
Original link:  http://www.prweb.com/releases/2015/03/prweb12556265.htm
 
Friends of Science Society is expressing alarm that President Barack Obama’s “Call out the Climate Change Deniers” web-site page is referencing what the Friends say is a non-existent 97% consensus.
They have sent a letter to Charles Bolden, Chief Administrator of NASA, asking him to revise this claim on the NASA web-site, wherein the 97% figure is drawn from a footnoted reference to three surveys. Friends of Science Society's research paper reveals the 97% claim is unsupported by evidence - “97% Consensus? NO! Global Warming Math Myths and Social Proofs.” Friends of Science note that citizens frequently refer to the NASA web-site as proof of a 97% consensus.

The alleged 97% scientific consensus on human-caused global warming is often cited as the justification for the imposition of carbon taxes and extreme climate change or greenhouse gas reduction targets as reported by The Guardian, May 16, 2013.

While many scientists can agree that human activities affect climate, there is vast disagreement about the scope of impact, the factors - such as carbon dioxide, deforestation, black carbon, or land disturbance - and to what extent humans can mitigate impact, or if it is even necessary, as evidenced by the 2008 US Senate Minority Report on Global Warming that cites some 650 scientists as dissenting on various aspects of the theory of human-caused global warming. Many refuted the impact of carbon dioxide (CO2).

A new Kindle book "Climate Change: The Facts" outlines some dissenting perspectives.

"The Neglected Sun: How the Sun Precludes Climate Catastrophe" by respected German industrialist and scientists Fritz Vahrenholt and Sebastien Luning explore solar influences on climate change.

Numerous peer-reviewed papers on solar influences on climate are posted by Club du Soleil
( chrono.qub.ac.uk/blaauw/cds.html )

The NASA Climate Change website refers to three separate studies as evidence of the alleged consensus, but Friends of Science says that their research reveals that none of these studies support the claim and no significant numbers of scientists have been surveyed on empirical questions to make such a claim.

According to a 2014 Congressional Research Study entitled “The US Science and Engineering Workforce," ...“In 2012, there were 6.2 million scientists and engineers (as defined in this report) employed in the United States” with some 4% or 248,000 working in the physical sciences.
Friends of Science says their review of the alleged ‘consensus’ surveys reveals manipulations of statistics, inconsistent terminology and definitions.

The Oreskes (2004) survey, reported in Science Magazine Dec. 3, 2004, claimed 75% and a “remarkable lack of disagreement” by the other 25% in the abstracts she reviewed. Peiser (2005) re-ran her survey and found only 1.2% or 13 scientists out of 1,117 agreed with the IPCC human-caused global warming declaration. At least 470 papers expressed no position on AGW whatsoever.
Doran & Zimmerman (2009) only assessed 79 scientists out of 3,146 respondents, asking two opinion questions about what should be an empirical, scientific topic. Many scientists refused to participate and dozens sent emails protesting the survey design, which can be read in the original thesis by M.K. Zimmerman.

In Anderegg et al (2010), only 66% of 1,372 climate scientists agreed with the IPCC 2007 declaration.

A more recent ‘consensus’ survey, not on NASA’s site, is also flawed, says Friends of Science, referring to their own study and a report in Forbes on May 30, 2013.

Friends of Science Society holds the position that the sun is the main driver of climate change, not human activity or CO2.

Friends of Science have spent a decade reviewing a broad spectrum of literature on climate change and have concluded the sun is the main driver of climate change, not carbon dioxide (CO2). The core group of the Friends of Science is made up of a growing group of Earth, atmospheric, astrophysical scientists and engineers who volunteer their time and resources to educate the public.
Friends of Science Society
P.O. Box 23167, Mission P.O.
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Toll-free Telephone: 1-888-789-9597
Web: friendsofscience.org
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at

Jupiter


From Wikipedia, the free encyclopedia

Jupiter Astronomical symbol of Jupiter
An image of Jupiter taken by New Horizons.
Jupiter as seen by New Horizons spacecraft during its gravity assist in 2007
Designations
Pronunciation Listeni/ˈdʒuːpɨtər/[1]
Adjectives Jovian
Orbital characteristics[5][a]
Epoch J2000
Aphelion 5.458104 AU (816520800 km)
Perihelion 4.950429 AU (740573600 km)
5.204267 AU (778547200 km)
Eccentricity 0.048775
398.88 d[3]
Average orbital speed
 13.07 km/s[3]
18.818°
Inclination
100.492°
275.066°
Known satellites 67 (as of 2014)
Physical characteristics
Mean radius
 69911±6 km[6][b]
Equatorial radius
Polar radius
  • 66854±10 km[6][b]
  • 10.517 Earths
Flattening 0.06487±0.00015
  • 6.1419×1010 km2[b][7]
  • 121.9 Earths
Volume
  • 1.4313×1015 km3[3][b]
  • 1321.3 Earths
Mass
  • 1.8986×1027 kg[3]
  • 317.8 Earths
  • 1/1047 Sun[8]
Mean density
 1.326 g/cm3[3][b]
24.79 m/s2[3][b]
2.528 g
59.5 km/s[3][b]
Sidereal rotation period
 9.925 h[9] (9 h 55 m 30 s)
Equatorial rotation velocity
 12.6 km/s
45300 km/h
3.13°[3]
North pole right ascension
 268.057°
17h 52m 14s[6]
North pole declination
 64.496°[6]
Albedo 0.343 (Bond)
0.52 (geom.)[3]
Surface temp. min mean max
1 bar level 165 K (−108.15°C)[3]
0.1 bar 112 K[3]
−1.6 to −2.94[3]
29.8″ to 50.1″[3]
Atmosphere[3]
Surface pressure
 20–200 kPa[10] (cloud layer)
27 km
Composition by volume by volume:
89.8±2.0% hydrogen (H2)
10.2±2.0% helium (He)
≈ 0.3% methane (CH4)
≈ 0.026% ammonia (NH3)
≈ 0.003% hydrogen deuteride (HD)
0.0006% ethane (C2H6)
0.0004% water (H2O)
Ices:
Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a giant planet with a mass one-thousandth of that of the Sun, but is two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn (Uranus and Neptune are ice giants). Jupiter was known to astronomers of ancient times.[11] The Romans named it after their god Jupiter.[12] When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough to cast shadows,[13] and making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. It may also have a rocky core of heavier elements,[14] but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it possesses a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury.

Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.

Structure

Jupiter is composed primarily of gaseous and liquid matter. It is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km (88,846 mi) at its equator. The density of Jupiter, 1.326 g/cm3, is the second highest of the giant planets, but lower than those of any of the four terrestrial planets.

Composition

Jupiter's upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules. Because a helium atom has about four times as much mass as a hydrogen atom, the composition changes when described as the proportion of mass contributed by different atoms. Thus, the atmosphere is approximately 75% hydrogen and 24% helium by mass, with the remaining one percent of the mass consisting of other elements. The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. The outermost layer of the atmosphere contains crystals of frozen ammonia.[15][16] Through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found.[17]

The atmospheric proportions of hydrogen and helium are close to the theoretical composition of the primordial solar nebula. Neon in the upper atmosphere only consists of 20 parts per million by mass, which is about a tenth as abundant as in the Sun.[18] Helium is also depleted, to about 80% of the Sun's helium composition. This depletion is a result of precipitation of these elements into the interior of the planet.[19] Abundances of heavier inert gases in Jupiter's atmosphere are about two to three times that of the Sun.

Based on spectroscopy, Saturn is thought to be similar in composition to Jupiter, but the other giant planets Uranus and Neptune have relatively much less hydrogen and helium.[20] Because of the lack of atmospheric entry probes, high-quality abundance numbers of the heavier elements are lacking for the outer planets beyond Jupiter.

Mass and size


Jupiter's diameter is one order of magnitude smaller (×0.10045) than the Sun, and one order of magnitude larger (×10.9733) than the Earth. The Great Red Spot has roughly the same size as the circumference of the Earth.

Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center. Although this planet dwarfs the Earth with a diameter 11 times as great, it is considerably less dense. Jupiter's volume is that of about 1,321 Earths, but it is only 318 times as massive.[3][21] Jupiter's radius is about 1/10 the radius of the Sun,[22] and its mass is 0.001 times the mass of the Sun, so the density of the two bodies is similar.[23] A "Jupiter mass" (MJ or MJup) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs. So, for example, the extrasolar planet HD 209458 b has a mass of 0.69 MJ, while Kappa Andromedae b has a mass of 12.8 MJ.[24]

Theoretical models indicate that if Jupiter had much more mass than it does at present, it would shrink.[25] For small changes in mass, the radius would not change appreciably, and above about 500 M⊕ (1.6 Jupiter masses)[25] the interior would become so much more compressed under the increased pressure that its volume would decrease despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve.[26] The process of further shrinkage with increasing mass would continue until appreciable stellar ignition is achieved as in high-mass brown dwarfs having around 50 Jupiter masses.[27]

Although Jupiter would need to be about 75 times as massive to fuse hydrogen and become a star, the smallest red dwarf is only about 30 percent larger in radius than Jupiter.[28][29] Despite this, Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside it is similar to the total solar radiation it receives.[30] This additional heat is generated by the Kelvin–Helmholtz mechanism through contraction. This process causes Jupiter to shrink by about 2 cm each year.[31]
When it was first formed, Jupiter was much hotter and was about twice its current diameter.[32]

Internal structure

Jupiter is thought to consist of a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen.[31]
Beyond this basic outline, there is still considerable uncertainty. The core is often described as rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths (see below). In 1997, the existence of the core was suggested by gravitational measurements,[31] indicating a mass of from 12 to 45 times the Earth's mass or roughly 4%–14% of the total mass of Jupiter.[30][33] The presence of a core during at least part of Jupiter's history is suggested by models of planetary formation that require the formation of a rocky or icy core massive enough to collect its bulk of hydrogen and helium from the protosolar nebula. Assuming it did exist, it may have shrunk as convection currents of hot liquid metallic hydrogen mixed with the molten core and carried its contents to higher levels in the planetary interior. A core may now be entirely absent, as gravitational measurements are not yet precise enough to rule that possibility out entirely.[31][34]

The uncertainty of the models is tied to the error margin in hitherto measured parameters: one of the rotational coefficients (J6) used to describe the planet's gravitational moment, Jupiter's equatorial radius, and its temperature at 1 bar pressure. The Juno mission, which launched in August 2011, is expected to better constrain the values of these parameters, and thereby make progress on the problem of the core.[35]

The core region is surrounded by dense metallic hydrogen, which extends outward to about 78% of the radius of the planet.[30] Rain-like droplets of helium and neon precipitate downward through this layer, depleting the abundance of these elements in the upper atmosphere.[19][36]

Above the layer of metallic hydrogen lies a transparent interior atmosphere of hydrogen. At this depth, the temperature is above the critical temperature, which for hydrogen is only 33 K[37] (see hydrogen). In this state, there are no distinct liquid and gas phases—hydrogen is said to be in a supercritical fluid state. It is convenient to treat hydrogen as gas in the upper layer extending downward from the cloud layer to a depth of about 1,000 km,[30] and as liquid in deeper layers. Physically, there is no clear boundary—the gas smoothly becomes hotter and denser as one descends.[38][39]

The temperature and pressure inside Jupiter increase steadily toward the core, due to the Kelvin–Helmholtz mechanism. At the "surface" pressure level of 10 bars, the temperature is around 340 K (67 °C; 152 °F). At the phase transition region where hydrogen—heated beyond its critical point—becomes metallic, it is believed the temperature is 10,000 K (9,700 °C; 17,500 °F) and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure is roughly 3,000–4,500 GPa.[30]
Diagram of Jupiter's moons, surface, and interior
This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen.

Atmosphere

Jupiter has the largest planetary atmosphere in the Solar System, spanning over 5,000 km (3,107 mi) in altitude.[40][41] As Jupiter has no surface, the base of its atmosphere is usually considered to be the point at which atmospheric pressure is equal to 1 MPa (10 bar), or ten times surface pressure on Earth.[40]

Cloud layers


This view of Jupiter's Great Red Spot and its surroundings was obtained by Voyager 1 on February 25, 1979, when the spacecraft was 9.2 million km (5.7 million mi) from Jupiter. The white oval storm directly below the Great Red Spot is approximately the same diameter as Earth.

Jupiter is perpetually covered with clouds composed of ammonia crystals and possibly ammonium hydrosulfide. The clouds are located in the tropopause and are arranged into bands of different latitudes, known as tropical regions. These are sub-divided into lighter-hued zones and darker belts. The interactions of these conflicting circulation patterns cause storms and turbulence. Wind speeds of 100 m/s (360 km/h) are common in zonal jets.[42] The zones have been observed to vary in width, color and intensity from year to year, but they have remained sufficiently stable for astronomers to give them identifying designations.[21]
This looping animation shows the movement of Jupiter's counter-rotating cloud bands. In this image, the planet's exterior is mapped onto a cylindrical projection. Animation at larger widths: 720 pixels, 1799 pixels.

The cloud layer is only about 50 km (31 mi) deep, and consists of at least two decks of clouds: a thick lower deck and a thin clearer region. There may also be a thin layer of water clouds underlying the ammonia layer, as evidenced by flashes of lightning detected in the atmosphere of Jupiter. This is caused by water's polarity, which makes it capable of creating the charge separation needed to produce lightning.[30] These electrical discharges can be up to a thousand times as powerful as lightning on the Earth.[43] The water clouds can form thunderstorms driven by the heat rising from the interior.[44]

The orange and brown coloration in the clouds of Jupiter are caused by upwelling compounds that change color when they are exposed to ultraviolet light from the Sun. The exact makeup remains uncertain, but the substances are believed to be phosphorus, sulfur or possibly hydrocarbons.[30][45] These colorful compounds, known as chromophores, mix with the warmer, lower deck of clouds. The zones are formed when rising convection cells form crystallizing ammonia that masks out these lower clouds from view.[46]

Jupiter's low axial tilt means that the poles constantly receive less solar radiation than at the planet's equatorial region. Convection within the interior of the planet transports more energy to the poles, balancing out the temperatures at the cloud layer.[21]

Great Red Spot and other vortices


Jupiter – Great Red Spot is decreasing in size (May 15, 2014).[47]

The best known feature of Jupiter is the Great Red Spot, a persistent anticyclonic storm that is larger than Earth, located 22° south of the equator. Latest evidence by the Hubble Space Telescope shows there are three "red spots" adjacent to the Great Red Spot[48] It is known to have been in existence since at least 1831,[49] and possibly since 1665.[50][51] Mathematical models suggest that the storm is stable and may be a permanent feature of the planet.[52] The storm is large enough to be visible through Earth-based telescopes with an aperture of 12 cm or larger.[53]
Time-lapse sequence (over 1 month) from the approach of Voyager 1 to Jupiter, showing the motion of atmospheric bands, and circulation of the Great Red Spot.
The oval object rotates counterclockwise, with a period of about six days.[54] The Great Red Spot's dimensions are 24–40,000 km × 12–14,000 km. It is large enough to contain two or three planets of Earth's diameter.[55] The maximum altitude of this storm is about 8 km (5 mi) above the surrounding cloudtops.[56]

Storms such as this are common within the turbulent atmospheres of giant planets. Jupiter also has white ovals and brown ovals, which are lesser unnamed storms. White ovals tend to consist of relatively cool clouds within the upper atmosphere. Brown ovals are warmer and located within the "normal cloud layer". Such storms can last as little as a few hours or stretch on for centuries.

Even before Voyager proved that the feature was a storm, there was strong evidence that the spot could not be associated with any deeper feature on the planet's surface, as the Spot rotates differentially with respect to the rest of the atmosphere, sometimes faster and sometimes more slowly. During its recorded history it has traveled several times around the planet relative to any possible fixed rotational marker below it.

In 2000, an atmospheric feature formed in the southern hemisphere that is similar in appearance to the Great Red Spot, but smaller. This was created when several smaller, white oval-shaped storms merged to form a single feature—these three smaller white ovals were first observed in 1938. The merged feature was named Oval BA, and has been nicknamed Red Spot Junior. It has since increased in intensity and changed color from white to red.[57][58][59]

Planetary rings


The rings of Jupiter

Jupiter has a faint planetary ring system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring.[60] These rings appear to be made of dust, rather than ice as with Saturn's rings.[30] The main ring is probably made of material ejected from the satellites Adrastea and Metis. Material that would normally fall back to the moon is pulled into Jupiter because of its strong gravitational influence. The orbit of the material veers towards Jupiter and new material is added by additional impacts.[61] In a similar way, the moons Thebe and Amalthea probably produce the two distinct components of the dusty gossamer ring.[61] There is also evidence of a rocky ring strung along Amalthea's orbit which may consist of collisional debris from that moon.[62]

Magnetosphere

Aurora on Jupiter. Three bright dots are created by magnetic flux tubes that connect to the Jovian moons Io (on the left), Ganymede (on the bottom) and Europa (also on the bottom). In addition, the very bright almost circular region, called the main oval, and the fainter polar aurora can be seen.

Jupiter's magnetic field is 14 times as strong as the Earth's, ranging from 4.2 gauss (0.42 mT) at the equator to 10–14 gauss (1.0–1.4 mT) at the poles, making it the strongest in the Solar System (except for sunspots).[46] This field is believed to be generated by eddy currents—swirling movements of conducting materials—within the liquid metallic hydrogen core. The volcanoes on the moon Io emit large amounts of sulfur dioxide forming a gas torus along the moon's orbit. The gas is ionized in the magnetosphere producing sulfur and oxygen ions. They, together with hydrogen ions originating from the atmosphere of Jupiter, form a plasma sheet in Jupiter's equatorial plane. The plasma in the sheet co-rotates with the planet causing deformation of the dipole magnetic field into that of magnetodisk. Electrons within the plasma sheet generate a strong radio signature that produces bursts in the range of 0.6–30 MHz.[63]

At about 75 Jupiter radii from the planet, the interaction of the magnetosphere with the solar wind generates a bow shock. Surrounding Jupiter's magnetosphere is a magnetopause, located at the inner edge of a magnetosheath—a region between it and the bow shock. The solar wind interacts with these regions, elongating the magnetosphere on Jupiter's lee side and extending it outward until it nearly reaches the orbit of Saturn. The four largest moons of Jupiter all orbit within the magnetosphere, which protects them from the solar wind.[30]

The magnetosphere of Jupiter is responsible for intense episodes of radio emission from the planet's polar regions. Volcanic activity on the Jovian moon Io (see below) injects gas into Jupiter's magnetosphere, producing a torus of particles about the planet. As Io moves through this torus, the interaction generates Alfvén waves that carry ionized matter into the polar regions of Jupiter. As a result, radio waves are generated through a cyclotron maser mechanism, and the energy is transmitted out along a cone-shaped surface. When the Earth intersects this cone, the radio emissions from Jupiter can exceed the solar radio output.[64]

Orbit and rotation


Jupiter (red) completes one orbit of the Sun (center) for every 11.86 orbits of the Earth (blue)

Jupiter is the only planet that has a center of mass with the Sun that lies outside the volume of the Sun, though by only 7% of the Sun's radius.[65] The average distance between Jupiter and the Sun is 778 million km (about 5.2 times the average distance from the Earth to the Sun, or 5.2 AU) and it completes an orbit every 11.86 years. This is two-fifths the orbital period of Saturn, forming a 5:2 orbital resonance between the two largest planets in the Solar System.[66] The elliptical orbit of Jupiter is inclined 1.31° compared to the Earth. Because of an eccentricity of 0.048, the distance from Jupiter and the Sun varies by 75 million km between perihelion and aphelion, or the nearest and most distant points of the planet along the orbital path respectively.

The axial tilt of Jupiter is relatively small: only 3.13°. As a result this planet does not experience significant seasonal changes, in contrast to Earth and Mars for example.[67]

Jupiter's rotation is the fastest of all the Solar System's planets, completing a rotation on its axis in slightly less than ten hours; this creates an equatorial bulge easily seen through an Earth-based amateur telescope. The planet is shaped as an oblate spheroid, meaning that the diameter across its equator is longer than the diameter measured between its poles. On Jupiter, the equatorial diameter is 9,275 km (5,763 mi) longer than the diameter measured through the poles.[39]

Because Jupiter is not a solid body, its upper atmosphere undergoes differential rotation. The rotation of Jupiter's polar atmosphere is about 5 minutes longer than that of the equatorial atmosphere; three systems are used as frames of reference, particularly when graphing the motion of atmospheric features. System I applies from the latitudes 10° N to 10° S; its period is the planet's shortest, at 9h 50m 30.0s. System II applies at all latitudes north and south of these; its period is 9h 55m 40.6s. System III was first defined by radio astronomers, and corresponds to the rotation of the planet's magnetosphere; its period is Jupiter's official rotation.[68]

Observation


Conjunction of Jupiter and the Moon

The retrograde motion of an outer planet is caused by its relative location with respect to the Earth.

Jupiter is usually the fourth brightest object in the sky (after the Sun, the Moon and Venus);[46] at times Mars appears brighter than Jupiter. Depending on Jupiter's position with respect to the Earth, it can vary in visual magnitude from as bright as −2.9 at opposition down to −1.6 during conjunction with the Sun. The angular diameter of Jupiter likewise varies from 50.1 to 29.8 arc seconds.[3] Favorable oppositions occur when Jupiter is passing through perihelion, an event that occurs once per orbit. As Jupiter approached perihelion in March 2011, there was a favorable opposition in September 2010.[69]

Earth overtakes Jupiter every 398.9 days as it orbits the Sun, a duration called the synodic period. As it does so, Jupiter appears to undergo retrograde motion with respect to the background stars. That is, for a period Jupiter seems to move backward in the night sky, performing a looping motion.

Jupiter's 12-year orbital period corresponds to the dozen astrological signs of the zodiac, and may have been the historical origin of the signs.[21] That is, each time Jupiter reaches opposition it has advanced eastward by about 30°, the width of a zodiac sign.

Because the orbit of Jupiter is outside the Earth's, the phase angle of Jupiter as viewed from the Earth never exceeds 11.5°. That is, the planet always appears nearly fully illuminated when viewed through Earth-based telescopes. It was only during spacecraft missions to Jupiter that crescent views of the planet were obtained.[70] A small telescope will usually show Jupiter's four Galilean moons and the prominent cloud belts across Jupiter's atmosphere.[71] A large telescope will show Jupiter's Great Red Spot when it faces the Earth.

Research and exploration

Pre-telescopic research


Model in the Almagest of the longitudinal motion of Jupiter (☉) relative to the Earth (⊕).

The observation of Jupiter dates back to the Babylonian astronomers of the 7th or 8th century BC.[72] The Chinese historian of astronomy, Xi Zezong, has claimed that Gan De, a Chinese astronomer, made the discovery of one of Jupiter's moons in 362 BC with the unaided eye. If accurate, this would predate Galileo's discovery by nearly two millennia.[73][74] In his 2nd century work the Almagest, the Hellenistic astronomer Claudius Ptolemaeus constructed a geocentric planetary model based on deferents and epicycles to explain Jupiter's motion relative to the Earth, giving its orbital period around the Earth as 4332.38 days, or 11.86 years.[75] In 499, Aryabhata, a mathematician-astronomer from the classical age of Indian mathematics and astronomy, also used a geocentric model to estimate Jupiter's period as 4332.2722 days, or 11.86 years.[76]

Ground-based telescope research

In 1610, Galileo Galilei discovered the four largest moons of Jupiter—Io, Europa, Ganymede and Callisto (now known as the Galilean moons)—using a telescope; thought to be the first telescopic observation of moons other than Earth's. Galileo's was also the first discovery of a celestial motion not apparently centered on the Earth. It was a major point in favor of Copernicus' heliocentric theory of the motions of the planets; Galileo's outspoken support of the Copernican theory placed him under the threat of the Inquisition.[77]

During the 1660s, Cassini used a new telescope to discover spots and colorful bands on Jupiter and observed that the planet appeared oblate; that is, flattened at the poles. He was also able to estimate the rotation period of the planet.[16] In 1690 Cassini noticed that the atmosphere undergoes differential rotation.[30]

False-color detail of Jupiter's atmosphere, imaged by Voyager 1, showing the Great Red Spot and a passing white oval.

The Great Red Spot, a prominent oval-shaped feature in the southern hemisphere of Jupiter, may have been observed as early as 1664 by Robert Hooke and in 1665 by Giovanni Cassini, although this is disputed. The pharmacist Heinrich Schwabe produced the earliest known drawing to show details of the Great Red Spot in 1831.[78]

The Red Spot was reportedly lost from sight on several occasions between 1665 and 1708 before becoming quite conspicuous in 1878. It was recorded as fading again in 1883 and at the start of the 20th century.[79]

Both Giovanni Borelli and Cassini made careful tables of the motions of the Jovian moons, allowing predictions of the times when the moons would pass before or behind the planet. By the 1670s, it was observed that when Jupiter was on the opposite side of the Sun from the Earth, these events would occur about 17 minutes later than expected. Ole Rømer deduced that sight is not instantaneous (a conclusion that Cassini had earlier rejected),[16] and this timing discrepancy was used to estimate the speed of light.[80]

In 1892, E. E. Barnard observed a fifth satellite of Jupiter with the 36-inch (910 mm) refractor at Lick Observatory in California. The discovery of this relatively small object, a testament to his keen eyesight, quickly made him famous. The moon was later named Amalthea.[81] It was the last planetary moon to be discovered directly by visual observation.[82] An additional eight satellites were subsequently discovered before the flyby of the Voyager 1 probe in 1979.

Infrared image of Jupiter taken by the ESO's Very Large Telescope.

In 1932, Rupert Wildt identified absorption bands of ammonia and methane in the spectra of Jupiter.[83]

Three long-lived anticyclonic features termed white ovals were observed in 1938. For several decades they remained as separate features in the atmosphere, sometimes approaching each other but never merging. Finally, two of the ovals merged in 1998, then absorbed the third in 2000, becoming Oval BA.[84]

Radiotelescope research

In 1955, Bernard Burke and Kenneth Franklin detected bursts of radio signals coming from Jupiter at 22.2 MHz.[30] The period of these bursts matched the rotation of the planet, and they were also able to use this information to refine the rotation rate. Radio bursts from Jupiter were found to come in two forms: long bursts (or L-bursts) lasting up to several seconds, and short bursts (or S-bursts) that had a duration of less than a hundredth of a second.[85]

Scientists discovered that there were three forms of radio signals transmitted from Jupiter.
  • Decametric radio bursts (with a wavelength of tens of meters) vary with the rotation of Jupiter, and are influenced by interaction of Io with Jupiter's magnetic field.[86]
  • Decimetric radio emission (with wavelengths measured in centimeters) was first observed by Frank Drake and Hein Hvatum in 1959.[30] The origin of this signal was from a torus-shaped belt around Jupiter's equator. This signal is caused by cyclotron radiation from electrons that are accelerated in Jupiter's magnetic field.[87]
  • Thermal radiation is produced by heat in the atmosphere of Jupiter.[30]

Exploration with space probes

Since 1973 a number of automated spacecraft have visited Jupiter, most notably the Pioneer 10 space probe, the first spacecraft to get close enough to Jupiter to send back revelations about the properties and phenomena of the Solar System's largest planet.[88][89] Flights to other planets within the Solar System are accomplished at a cost in energy, which is described by the net change in velocity of the spacecraft, or delta-v. Entering a Hohmann transfer orbit from Earth to Jupiter from low Earth orbit requires a delta-v of 6.3 km/s[90] which is comparable to the 9.7 km/s delta-v needed to reach low Earth orbit.[91] Fortunately, gravity assists through planetary flybys can be used to reduce the energy required to reach Jupiter, albeit at the cost of a significantly longer flight duration.[92]

Flyby missions

Flyby missions
Spacecraft Closest
approach		 Distance
Pioneer 10 December 3, 1973 130,000 km
Pioneer 11 December 4, 1974 34,000 km
Voyager 1 March 5, 1979 349,000 km
Voyager 2 July 9, 1979 570,000 km
Ulysses February 8, 1992[93] 408,894 km
February 4, 2004[93] 120,000,000 km
Cassini December 30, 2000 10,000,000 km
New Horizons February 28, 2007 2,304,535 km
Beginning in 1973, several spacecraft have performed planetary flyby maneuvers that brought them within observation range of Jupiter. The Pioneer missions obtained the first close-up images of Jupiter's atmosphere and several of its moons. They discovered that the radiation fields near the planet were much stronger than expected, but both spacecraft managed to survive in that environment. The trajectories of these spacecraft were used to refine the mass estimates of the Jovian system. Radio occultations by the planet resulted in better measurements of Jupiter's diameter and the amount of polar flattening.[21][94]

Six years later, the Voyager missions vastly improved the understanding of the Galilean moons and discovered Jupiter's rings. They also confirmed that the Great Red Spot was anticyclonic. Comparison of images showed that the Red Spot had changed hue since the Pioneer missions, turning from orange to dark brown. A torus of ionized atoms was discovered along Io's orbital path, and volcanoes were found on the moon's surface, some in the process of erupting. As the spacecraft passed behind the planet, it observed flashes of lightning in the night side atmosphere.[15][21]

The next mission to encounter Jupiter, the Ulysses solar probe, performed a flyby maneuver to attain a polar orbit around the Sun. During this pass the spacecraft conducted studies on Jupiter's magnetosphere. Since Ulysses has no cameras, no images were taken. A second flyby six years later was at a much greater distance.[93]

Cassini views Jupiter and Io on January 1, 2001

In 2000, the Cassini probe, en route to Saturn, flew by Jupiter and provided some of the highest-resolution images ever made of the planet. On December 19, 2000, the spacecraft captured an image of the moon Himalia, but the resolution was too low to show surface details.[95]

The New Horizons probe, en route to Pluto, flew by Jupiter for gravity assist. Its closest approach was on February 28, 2007.[96] The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail, as well as making long-distance observations of the outer moons Himalia and Elara.[97] Imaging of the Jovian system began September 4, 2006.[98][99]

Galileo mission

Jupiter as seen by the space probe Cassini.

So far the only spacecraft to orbit Jupiter is the Galileo orbiter, which went into orbit around Jupiter on December 7, 1995.[26] It orbited the planet for over seven years, conducting multiple flybys of all the Galilean moons and Amalthea. The spacecraft also witnessed the impact of Comet Shoemaker-Levy 9 as it approached Jupiter in 1994, giving a unique vantage point for the event. While the information gained about the Jovian system from Galileo was extensive, its originally designed capacity was limited by the failed deployment of its high-gain radio transmitting antenna.[100]

A 340-kilogram titanium atmospheric probe was released from the spacecraft in July 1995, entering Jupiter's atmosphere on December 7.[26] It parachuted through 150 km (93 mi) of the atmosphere at speed of about 2,575 km/h (1600 mph)[26] and collected data for 57.6 minutes before it was crushed by the pressure (about 23 times Earth normal, at a temperature of 153 °C).[101] It would have melted thereafter, and possibly vaporized. The Galileo orbiter itself experienced a more rapid version of the same fate when it was deliberately steered into the planet on September 21, 2003, at a speed of over 50 km/s, to avoid any possibility of it crashing into and possibly contaminating Europa—a moon which has been hypothesized to have the possibility of harboring life.[100]

Data from this mission revealed that hydrogen composes up to 90% of Jupiter's atmosphere.[26] The temperatures data recorded was more than 300°C (>570°F) and the windspeed measured more than 644 kmph (>400 mph) before the probes vapourised.[26]

Future probes

NASA has a mission underway to study Jupiter in detail from a polar orbit. Named Juno, the spacecraft launched in August 2011, and will arrive in late 2016.[102] The next planned mission to the Jovian system will be the European Space Agency's Jupiter Icy Moon Explorer (JUICE), due to launch in 2022.[103]

Canceled missions

Because of the possibility of subsurface liquid oceans on Jupiter's moons Europa, Ganymede and Callisto, there has been great interest in studying the icy moons in detail. Funding difficulties have delayed progress. NASA's JIMO (Jupiter Icy Moons Orbiter) was cancelled in 2005.[104] A subsequent proposal for a joint NASA/ESA mission, called EJSM/Laplace, was developed with a provisional launch date around 2020. EJSM/Laplace would have consisted of the NASA-led Jupiter Europa Orbiter, and the ESA-led Jupiter Ganymede Orbiter.[105] However by April 2011, ESA had formally ended the partnership citing budget issues at NASA and the consequences on the mission timetable. Instead ESA planned to go ahead with a European-only mission to compete in its L1 Cosmic Vision selection.[106]

Moons


Jupiter with the Galilean moons. Seen from Earth at this point in their orbits, Europa appears closer to Jupiter than does Io.

Jupiter has 67 natural satellites.[107] Of these, 51 are less than 10 kilometres in diameter and have only been discovered since 1975. The four largest moons, visible from Earth with binoculars on a clear night, known as the "Galilean moons", are Io, Europa, Ganymede and Callisto.

Galilean moons

The Galilean moons. From left to right, in order of increasing distance from Jupiter: Io, Europa, Ganymede, Callisto.

The orbits of Io, Europa, and Ganymede, some of the largest satellites in the Solar System, form a pattern known as a Laplace resonance; for every four orbits that Io makes around Jupiter, Europa makes exactly two orbits and Ganymede makes exactly one. This resonance causes the gravitational effects of the three large moons to distort their orbits into elliptical shapes, since each moon receives an extra tug from its neighbors at the same point in every orbit it makes. The tidal force from Jupiter, on the other hand, works to circularize their orbits.[108]

The eccentricity of their orbits causes regular flexing of the three moons' shapes, with Jupiter's gravity stretching them out as they approach it and allowing them to spring back to more spherical shapes as they swing away. This tidal flexing heats the moons' interiors by friction. This is seen most dramatically in the extraordinary volcanic activity of innermost Io (which is subject to the strongest tidal forces), and to a lesser degree in the geological youth of Europa's surface (indicating recent resurfacing of the moon's exterior).

The Galilean moons, compared to Earth's Moon
Name IPA Diameter Mass Orbital radius Orbital period
km  % kg  % km  % days  %
Io ˈaɪ.oʊ 3643 105 8.9×1022 120 421,700 110 1.77 7
Europa jʊˈroʊpə 3122 90 4.8×1022 65 671,034 175 3.55 13
Ganymede ˈɡænimiːd 5262 150 14.8×1022 200 1,070,412 280 7.15 26
Callisto kəˈlɪstoʊ 4821 140 10.8×1022 150 1,882,709 490 16.69 61

Classification of moons


Jupiter's moon Europa.

Before the discoveries of the Voyager missions, Jupiter's moons were arranged neatly into four groups of four, based on commonality of their orbital elements. Since then, the large number of new small outer moons has complicated this picture. There are now thought to be six main groups, although some are more distinct than others.

A basic sub-division is a grouping of the eight inner regular moons, which have nearly circular orbits near the plane of Jupiter's equator and are believed to have formed with Jupiter. The remainder of the moons consist of an unknown number of small irregular moons with elliptical and inclined orbits, which are believed to be captured asteroids or fragments of captured asteroids. Irregular moons that belong to a group share similar orbital elements and thus may have a common origin, perhaps as a larger moon or captured body that broke up.[109][110]

Regular moons
Inner group The inner group of four small moons all have diameters of less than 200 km, orbit at radii less than 200,000 km, and have orbital inclinations of less than half a degree.
Galilean moons[111] These four moons, discovered by Galileo Galilei and by Simon Marius in parallel, orbit between 400,000 and 2,000,000 km, and include some of the largest moons in the Solar System.
Irregular moons
Themisto This is a single moon belonging to a group of its own, orbiting halfway between the Galilean moons and the Himalia group.
Himalia group A tightly clustered group of moons with orbits around 11,000,000–12,000,000 km from Jupiter.
Carpo Another isolated case; at the inner edge of the Ananke group, it orbits Jupiter in prograde direction.
Ananke group This retrograde orbit group has rather indistinct borders, averaging 21,276,000 km from Jupiter with an average inclination of 149 degrees.
Carme group A fairly distinct retrograde group that averages 23,404,000 km from Jupiter with an average inclination of 165 degrees.
Pasiphaë group A dispersed and only vaguely distinct retrograde group that covers all the outermost moons.

Interaction with the Solar System

Along with the Sun, the gravitational influence of Jupiter has helped shape the Solar System. The orbits of most of the system's planets lie closer to Jupiter's orbital plane than the Sun's equatorial plane (Mercury is the only planet that is closer to the Sun's equator in orbital tilt), the Kirkwood gaps in the asteroid belt are mostly caused by Jupiter, and the planet may have been responsible for the Late Heavy Bombardment of the inner Solar System's history.[112]

This diagram shows the Trojan asteroids in Jupiter's orbit, as well as the main asteroid belt.

Along with its moons, Jupiter's gravitational field controls numerous asteroids that have settled into the regions of the Lagrangian points preceding and following Jupiter in its orbit around the Sun. These are known as the Trojan asteroids, and are divided into Greek and Trojan "camps" to commemorate the Iliad. The first of these, 588 Achilles, was discovered by Max Wolf in 1906; since then more than two thousand have been discovered.[113] The largest is 624 Hektor.

Most short-period comets belong to the Jupiter family—defined as comets with semi-major axes smaller than Jupiter's. Jupiter family comets are believed to form in the Kuiper belt outside the orbit of Neptune. During close encounters with Jupiter their orbits are perturbed into a smaller period and then circularized by regular gravitational interaction with the Sun and Jupiter.[114]

Impacts

Hubble image taken on July 23 showing a blemish of about 5,000 miles long left by the 2009 Jupiter impact.[115]

Jupiter has been called the Solar System's vacuum cleaner,[116] because of its immense gravity well and location near the inner Solar System. It receives the most frequent comet impacts of the Solar System's planets.[117] It was thought that the planet served to partially shield the inner system from cometary bombardment.[26] Recent computer simulations suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward in roughly the same numbers that it accretes or ejects them.[118] This topic remains controversial among astronomers, as some believe it draws comets towards Earth from the Kuiper belt while others believe that Jupiter protects Earth from the alleged Oort cloud.[119] Jupiter experiences about 200 times more asteroid and comet impacts than Earth.[26]

A 1997 survey of historical astronomical drawings suggested that the astronomer Cassini may have recorded an impact scar in 1690. The survey determined eight other candidate observations had low or no possibilities of an impact.[120] A fireball was photographed by Voyager 1 during its Jupiter encounter in March 1979.[121] During the period July 16, 1994, to July 22, 1994, over 20 fragments from the comet Shoemaker–Levy 9 (SL9, formally designated D/1993 F2) collided with Jupiter's southern hemisphere, providing the first direct observation of a collision between two Solar System objects. This impact provided useful data on the composition of Jupiter's atmosphere.[122][123]

On July 19, 2009, an impact site was discovered at approximately 216 degrees longitude in System 2.[124][125] This impact left behind a black spot in Jupiter's atmosphere, similar in size to Oval BA. Infrared observation showed a bright spot where the impact took place, meaning the impact warmed up the lower atmosphere in the area near Jupiter's south pole.[126]

A fireball, smaller than the previous observed impacts, was detected on June 3, 2010, by Anthony Wesley, an amateur astronomer in Australia, and was later discovered to have been captured on video by another amateur astronomer in the Philippines.[127] Yet another fireball was seen on August 20, 2010.[128]

On September 10, 2012, another fireball was detected.[121][129]

Possibility of life

In 1953, the Miller–Urey experiment demonstrated that a combination of lightning and the chemical compounds that existed in the atmosphere of a primordial Earth could form organic compounds (including amino acids) that could serve as the building blocks of life. The simulated atmosphere included water, methane, ammonia and molecular hydrogen; all molecules still found in the atmosphere of Jupiter. The atmosphere of Jupiter has a strong vertical air circulation, which would carry these compounds down into the lower regions. The higher temperatures within the interior of the atmosphere breaks down these chemicals, which would hinder the formation of Earth-like life.[130]
It is considered highly unlikely that there is any Earth-like life on Jupiter, as there is only a small amount of water in the atmosphere and any possible solid surface deep within Jupiter would be under extraordinary pressures. In 1976, before the Voyager missions, it was hypothesized that ammonia or water-based life could evolve in Jupiter's upper atmosphere. This hypothesis is based on the ecology of terrestrial seas which have simple photosynthetic plankton at the top level, fish at lower levels feeding on these creatures, and marine predators which hunt the fish.[131][132]

The possible presence of underground oceans on some of Jupiter's moons has led to speculation that the presence of life is more likely there.

Mythology


Jupiter, woodcut from a 1550 edition of Guido Bonatti's Liber Astronomiae.

The planet Jupiter has been known since ancient times. It is visible to the naked eye in the night sky and can occasionally be seen in the daytime when the Sun is low.[133] To the Babylonians, this object represented their god Marduk. They used the roughly 12-year orbit of this planet along the ecliptic to define the constellations of their zodiac.[21][134]

The Romans named it after Jupiter (Latin: Iuppiter, Iūpiter) (also called Jove), the principal god of Roman mythology, whose name comes from the Proto-Indo-European vocative compound *Dyēu-pəter (nominative: *Dyēus-pətēr, meaning "O Father Sky-God", or "O Father Day-God").[135] In turn, Jupiter was the counterpart to the mythical Greek Zeus (Ζεύς), also referred to as Dias (Δίας), the planetary name of which is retained in modern Greek.[136]

The astronomical symbol for the planet, ♃, is a stylized representation of the god's lightning bolt. The original Greek deity Zeus supplies the root zeno-, used to form some Jupiter-related words, such as zenographic.[137]

Jovian is the adjectival form of Jupiter. The older adjectival form jovial, employed by astrologers in the Middle Ages, has come to mean "happy" or "merry," moods ascribed to Jupiter's astrological influence.[138]

The Chinese, Korean and Japanese referred to the planet as the "wood star" (Chinese: 木星; pinyin: mùxīng), based on the Chinese Five Elements.[139] Chinese Taoism personified it as the Fu star. The Greeks called it Φαέθων, Phaethon, "blazing." In Vedic Astrology, Hindu astrologers named the planet after Brihaspati, the religious teacher of the gods, and often called it "Guru", which literally means the "Heavy One."[140] In the English language, Thursday is derived from "Thor's day", with Thor associated with the planet Jupiter in Germanic mythology.[141]

In the Central Asian-Turkic myths, Jupiter called as a "Erendiz/Erentüz", which means "eren(?)+yultuz(star)". There are many theories about meaning of "eren". Also, these peoples calculated the period of the orbit of Jupiter as 11 years and 300 days. They believed that some social and natural events connected to Erentüz's movements on the sky.[142]

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