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121-460: Download coordinates as: Operation Fishbowl was a series of high-altitude nuclear tests in 1962 that were carried out by the United States as a part of the larger Operation Dominic nuclear test program. The Operation Fishbowl nuclear tests were originally to be completed during the first half of 1962 with three tests named Bluegill, Starfish and Urraca . The first test attempt

242-456: A ring current . This current reduces the magnetic field at the Earth's surface. Particles that penetrate the ionosphere and collide with the atoms there give rise to the lights of the aurorae while also emitting X-rays . 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

363-470: A fire that burned down the Karaganda power plant, and shut down 1,000 kilometres (620 mi) of shallow-buried power cables between Tselinograd and Alma-Ata . US Government Films: Earth%27s magnetic field Earth's magnetic field , also known as the geomagnetic field , is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind ,

484-463: A form of saber rattling. The worst effects of a Soviet high-altitude test occurred on 22 October 1962, in the Soviet Project K nuclear tests (ABM System A proof tests) when a 300 kt missile-warhead detonated near Dzhezkazgan at 290-kilometre (180 mi) altitude. The EMP fused 570 kilometres (350 mi) of overhead telephone line with a measured current of 2,500  A , started

605-497: A green and blue circular region surrounded by a blood-red ring formed overhead that faded in less than one minute. Blue-green streamers and numerous pink striations formed, the latter lasting for 30 minutes. Observers at Samoa saw a white flash, which faded to orange and disappeared in about one minute." The fourth attempt at the Bluegill test was launched on a Thor missile on October 25, 1962 (Johnston Island time). It resulted in

726-527: A large number of surface and aircraft-based stations in the wide area around the planned detonations and also in the region in the southern hemisphere in the Samoan Islands region, which was known in these tests as the southern conjugate region . Johnston Island is in the northern hemisphere, as were all of the planned Operation Fishbowl nuclear detonation locations. It was known from previous high altitude tests, as well as from theoretical work done in

847-408: A normal trajectory for 59 seconds; then the rocket engine suddenly stopped, and the missile began to break apart. The range safety officer ordered the destruction of the missile and the warhead. The missile was between 30,000 and 35,000 feet (between 9.1 and 10.7 km) in altitude when it was destroyed. Some of the missile parts fell on Johnston Island, and a large amount of missile debris fell into

968-413: 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

1089-400: A presently accelerating rate—10 kilometres (6.2 mi) per year at the beginning of the 1900s, up to 40 kilometres (25 mi) per year in 2003, and since then has only accelerated. The Earth's magnetic field is believed to be generated by electric currents in the conductive iron alloys of its core, created by convection currents due to heat escaping from the core. The Earth and most of

1210-499: A region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination). Components of the Earth's magnetic field at the surface from the World Magnetic Model for 2020. 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

1331-456: A simple compass can remain useful for navigation. Using magnetoreception , various other organisms, ranging from some types of bacteria to pigeons, use the Earth's magnetic field for orientation and navigation. 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

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1452-480: A spherical 'cloud' until distorted by Earth's magnetic field . The charged particles resulting from the blast are accelerated along the Earth's magnetic field lines to create an auroral display at the conjugate point , which has led documentary maker Peter Kuran to characterize these detonations as 'the rainbow bombs'. The visual effects of a high-altitude or space-based explosion may last longer than atmospheric tests, sometimes in excess of 30 minutes. Heat from

1573-495: A spiral along the magnetic field lines in the Earth's magnetic field. The nuclear explosions also release heavier debris ions , which also carry an electrical charge, and which also travel in a spiral along the Earth's magnetic field lines. The Earth's magnetic field lines arc high above the Earth until they reach the magnetic conjugate area in the opposite hemisphere. According to the DOD nuclear weapon effects reference, "Because

1694-572: A stream of charged particles emanating from the Sun . The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core : these convection currents are caused by heat escaping from the core, a natural process called a geodynamo . The magnitude of Earth's magnetic field at its surface ranges from 25 to 65 μT (0.25 to 0.65 G). As an approximation, it

1815-422: A successful detonation of a submegaton nuclear warhead at about one minute before midnight, local time (the official Coordinated Universal Time was 0959 on October 26, 1962). It was officially reported as being in the submegaton range (meaning more than 200 kilotons but less than one megaton), and most observers of the U.S. nuclear testing programs believe that the nuclear yield was about 400 kilotons. One report by

1936-596: A third of NASA's satellites. The largest documented storm, the Carrington Event , occurred in 1859. It induced currents strong enough to disrupt telegraph lines, and aurorae were reported as far south as Hawaii. 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

2057-464: A year or more mostly reflect changes in the Earth's interior , particularly the iron-rich core . 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 . Data from THEMIS show that the magnetic field, which interacts with the solar wind, is reduced when

2178-399: A yellow-white, luminous circle with intense purple streamers for the first minute. Some of the streamers displayed what appeared to be a rapid twisting motion at times. A large pale-green patch appeared somewhat south of the burst and grew, becoming the dominant visible feature after 5 minutes. By H+1 the green had become dull gray, but the feature persisted for 3 hours. At Oahu a bright flash

2299-463: 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. 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

2420-548: 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. 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

2541-453: 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. A dynamo can amplify a magnetic field, but it needs a "seed" field to get it started. 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

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2662-431: Is called detrital remanent magnetization . Thermoremanent magnetization is the main source of the magnetic anomalies around mid-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

2783-402: 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). 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

2904-408: Is generally reported in microteslas (μT), with 1 G = 100 μT. A nanotesla is also referred to as a gamma (γ). The Earth's field ranges between approximately 22 and 67 μT (0.22 and 0.67 G). By comparison, a strong refrigerator magnet has a field of about 10,000 μT (100 G). A map of intensity contours is called an isodynamic chart . As the World Magnetic Model shows,

3025-518: Is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the center of Earth. The North geomagnetic pole ( Ellesmere Island , Nunavut , Canada) actually represents the South pole of Earth's magnetic field, and conversely the South geomagnetic pole corresponds to

3146-407: Is shown below . 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

3267-600: 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. 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 . In 2024 researchers published evidence from Greenland for

3388-464: 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

3509-420: 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. The intensity of the field is often measured in gauss (G) , but

3630-752: The Bluegill Triple Prime shot, at an altitude of 50 kilometers (31 miles), was felt by personnel on the ground at Johnston Atoll , and this test caused retina burns to two personnel at ground zero who were not wearing their safety goggles. The Soviets detonated four high-altitude tests in 1961 and three in 1962. During the Cuban Missile Crisis in October 1962, both the US and the USSR detonated several high-altitude nuclear explosions as

3751-629: The Bluegill Triple Prime and Kingfish data. (The report actually using the Bluegill Triple Prime and Kingfish data to confirm the new EMP theory is the still-classified Part 2 of the unclassified report by Conrad Longmire.) According to a Sandia National Laboratories report, EMP generated during the Operation Fishbowl tests caused "input circuit troubles in radio receivers during the Starfish and Checkmat e bursts;

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3872-464: The Bluegill Triple Prime test. Neither individual had his protective goggles in place at the instant of the detonation. One official report stated, "In the first case, acuity for central vision was 20/400 initially, but returned to 20/25 by six months. The second victim was less fortunate, as central vision did not improve beyond 20/60. The lesion diameters were 0.35 and 0.50 mm respectively. Both individuals noted immediate visual disturbances, but neither

3993-497: The Bluegill, Kingfish and Checkmate tests, "the thermal-pulse durations are of the same order of magnitude or shorter than the natural blink period which, for the average person, is about 150 milliseconds. Furthermore, the atmospheric attenuation is normally much less for a given distance than in the case of sea-level or near-sea-level explosions. Consequently, the eye-damage hazard is more severe." Two cases of retinal damage did occur with military personnel on Johnston Island during

4114-490: The Boothia Peninsula in 1831 to 600 kilometres (370 mi) from Resolute Bay in 2001. The magnetic equator is the line where the inclination is zero (the magnetic field is horizontal). 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

4235-505: The Brunhes–Matuyama reversal , occurred about 780,000 years ago. A related phenomenon, a geomagnetic excursion , takes the dipole axis across the equator and then back to the original polarity. The Laschamp event is an example of an excursion, occurring during the last ice age (41,000 years ago). The past magnetic field is recorded mostly by strongly magnetic minerals , particularly iron oxides such as magnetite , that can carry

4356-470: The North and South Magnetic Poles abruptly switch places. These reversals of the geomagnetic poles leave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past. Such information in turn is helpful in studying the motions of continents and ocean floors. The magnetosphere is defined by the extent of Earth's magnetic field in space or geospace . It extends above

4477-554: The Soviet Union was stationed near Johnston Island for the test and another Soviet scientific expeditionary ship was located in the southern conjugate region, permanent features of all future oceanic nuclear testing. After the Starfish Prime detonation, bright auroras were observed in the detonation area as well as in the southern conjugate region on the other side of the equator from the detonation. According to one of

4598-710: The Starfish Prime radiation, with its complete failure occurring on February 21, 1963. In 2010, the United States Defense Threat Reduction Agency issued a report that had been written in support of the United States Commission to Assess the Threat to the United States from Electromagnetic Pulse Attack. The report, entitled "Collateral Damage to Satellites from an EMP Attack," discusses in great detail

4719-406: The Starfish Prime test. Prompt gamma ray output measurements on these later tests were also carefully obtained so that a new theory of the mechanism for high-altitude EMP could be developed and confirmed. That new theory about the generation of nuclear EMP was developed by Los Alamos physicist Conrad Longmire in 1963, and it is the high-altitude nuclear EMP theory that is still used today. As of

4840-426: The beta particles have high velocities, the beta auroras in the remote (southern) hemisphere appeared within a fraction of a second of those in the hemisphere where the burst had occurred. The debris ions, however, travel more slowly and so the debris aurora in the remote hemisphere, if it is formed, appears at a somewhat later time. The beta auroras are generally most intense at an altitude of 30 to 60 miles, whereas

4961-483: The electrical conductivity σ and the permeability μ . The term ∂ B /∂ t is the partial derivative of the field with respect to time; ∇ is the Laplace operator , ∇× is the curl operator , and × is the vector product . 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

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5082-402: The ionosphere , several tens of thousands of kilometres into space , protecting Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects Earth from harmful ultraviolet radiation . Earth's magnetic field deflects most of the solar wind, whose charged particles would otherwise strip away

5203-471: The magnetic field lines, where they can persist for long periods of time (up to several months or longer), forming artificial radiation belts . According to the Operation Fishbowl planning document of November 1961, "Since much valuable data can be obtained from time and spectrum resolved photography, this dictates that the test be performed at nighttime when auroral photographic conditions are best." As with all U.S. Pacific high-altitude nuclear tests, all of

5324-402: The Earth's dynamo shut off, the dipole part would disappear in a few tens of thousands of years. 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

5445-420: The Earth's magnetic field cycles with intensity every 200 million years. The lead author stated that "Our findings, when considered alongside the existing datasets, support the existence of an approximately 200-million-year-long cycle in the strength of the Earth's magnetic field related to deep Earth processes." The inclination is given by an angle that can assume values between −90° (up) to 90° (down). In

5566-434: 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. Sunward of the magnetopause is the bow shock , the area where the solar wind slows abruptly. Inside

5687-437: 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. Earth's magnetic field, predominantly dipolar at its surface,

5808-771: The Earth's surface. The potential as an anti-satellite weapon became apparent in August 1958 during Hardtack Teak . The EMP observed at the Apia Observatory at Samoa was four times more powerful than any created by solar storms , while in July 1962 the Starfish Prime test damaged electronics in Honolulu and New Zealand (approximately 1,300 kilometres (810 mi) away), fused 300 street lights on Oahu (Hawaii), set off about 100 burglar alarms , and caused

5929-560: The Johnston Island area and across the nearby North Pacific region, including the primary instrumentation ship USAS American Mariner providing measurements conducted by personnel provided by RCA Service Company and Barnes Engineering Company. A few military ships and aircraft were also positioned in the southern conjugate region for the test, which was near the Samoan Islands. In addition, an uninvited observation ship from

6050-462: The Operation Fishbowl plan was made during an 82-day operations pause after the Bluegill Prime disaster of July 25, 1962, as described below. A test named Kingfish was added during the early stages of Operation Fishbowl planning. Two low-yield tests, Checkmate and Tightrope , were also added during the project, so the final number of tests in Operation Fishbowl was five. Tightrope was

6171-442: The Operation Fishbowl tests were completed at night. This is in contrast to the high-altitude nuclear tests of the Soviet Project K nuclear tests , which were done over the populated land region of central Kazakhstan , and therefore had to be done during the daytime to avoid eyeburn damage to the population from the very bright flash of high-altitude nuclear explosions (as discussed in the introduction to this article). According to

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6292-657: The Pacific Ocean north of the equator. Johnston Island had already been established as a launch site for United States high-altitude nuclear tests, rather than the other locations in the Pacific Proving Grounds . In 1958, Lewis Strauss , then chairman of the United States Atomic Energy Commission , opposed doing any high-altitude tests at locations that had been used for earlier Pacific nuclear tests. His opposition

6413-571: The Solar System by the Sun's magnetosphere, or heliosphere . 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. 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

6534-518: The Thor missile. Starfish Prime caused an electromagnetic pulse (EMP) which was far larger than expected, so much larger that it drove much of the instrumentation off scale, causing great difficulty in getting accurate measurements. The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (900 mi) away from

6655-556: The U.S. federal government reported the Tightrope test yield as 10 kilotons. High-altitude nuclear explosion The Partial Test Ban Treaty was passed in October 1963, ending atmospheric and exoatmospheric nuclear tests. The Outer Space Treaty of 1967 banned the stationing of nuclear weapons in space, in addition to other weapons of mass destruction . The Comprehensive Nuclear-Test-Ban Treaty of 1996 prohibits all nuclear testing; whether over- or underground, underwater or in

6776-421: The U.S. federal government reported the test yield as 200 kilotons. Since all of the Operation Fishbowl tests were planned to occur during the night, the potential for eyeburn, especially for permanent retinal damage, was an important consideration at all levels of planning. Much research went into the potential eyeburn problem. One of the official reports for the project stated that, for the altitudes planned for

6897-529: The United Kingdom satellite Ariel . It also damaged the Soviet satellite Cosmos V . All of these satellites failed completely within several months of the Starfish detonation. There is also evidence that the Starfish Prime radiation belt may have damaged the satellites Explorer 14, Explorer 15 and Relay 1 . Telstar I lasted the longest of the satellites that were clearly damaged by

7018-471: The area by alpha-emitting core materials. Burning rocket fuel, flowing through the cable trenches, caused extensive chemical contamination of the trenches and the equipment associated with the cabling in the trenches. The radioactive contamination on Johnston Island was determined to be a major problem, and it was necessary to decontaminate the entire area before the badly damaged launch pad could be rebuilt. Operation Fishbowl test operations stopped after

7139-518: The atmosphere and collide with air molecules, depositing their energy to produce huge quantities of positive ions and recoil electrons (also known as Compton electrons ). These MeV-energy Compton electrons then accelerate and spiral along the Earth's magnetic field lines. The resulting transient electric fields and currents generate electromagnetic emissions in the radio frequency range of 15 MHz to 250 MHz . This high-altitude EMP occurs between 30 and 50 kilometers (19 and 31 miles) above

7260-593: The atmosphere in the northern hemisphere between Johnston Island and the main Hawaiian Islands , whereas the conjugate region was in the vicinity of the Samoan , Fiji , and Tonga Islands. It is in these areas that auroras were actually observed, in addition to those in the areas of the nuclear explosions." Beta particles are charged particles (usually with a negative electrical charge ) that are released from nuclear explosions. These particles travel in

7381-478: The atmosphere, but hasn't entered into force yet as it hasn't been ratified by some of the states party to the Treaty. The strong electromagnetic pulse (EMP) that results has several components. In the first few tenths of nanoseconds, about a tenth of a percent of the weapon yield appears as powerful gamma rays with energies of one to three mega-electron volts ( MeV , a unit of energy). The gamma rays penetrate

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7502-407: The basis for magnetostratigraphy , a way of dating rocks and sediments. The field also magnetizes the crust, and magnetic anomalies can be used to search for deposits of metal ores . Humans have used compasses for direction finding since the 11th century A.D. and for navigation since the 12th century. Although the magnetic declination does shift with time, this wandering is slow enough that

7623-476: The beginning of 2011, the EMP waveforms and prompt gamma radiation outputs for Bluegill Triple Prime and Kingfish remain classified. An unclassified report confirms that these measurements were successfully made and that a subsequent theory (which is the one now used) was developed which describes the mechanism by which the high-altitude EMP is generated. That new theory does give results which are consistent with both

7744-435: The current strength are within the normal range of variation, as shown by the record of past magnetic fields recorded in rocks. The nature of Earth's magnetic field is one of heteroscedastic (seemingly random) 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

7865-413: The destruct command, which split the rocket and ruptured both fuel tanks, completely destroying the missile and badly damaging the launch pad. The warhead charges also exploded asymmetrically and sprayed the area with the moderately radioactive core materials. Although there was little danger of an accidental nuclear explosion, the destruction of the nuclear warhead on the launch pad caused contamination of

7986-455: The detonation point, knocking out about 300 streetlights, setting off numerous burglar alarms and damaging a telephone company microwave link (the detonation time was nine seconds after 11 p.m. in Hawaii). A total of 27 sounding rockets were launched from Johnston Island to obtain experimental data from the shot, with the first of the support rockets being launched 2 hours and 45 minutes before

8107-603: The disastrous failure of Bluegill Prime , and most of the personnel not directly involved in the radioactive cleanup and launch pad rebuild on Johnston Island returned to their home stations to await the resumption of tests. According to the Operation Dominic I report, "The enforced pause allowed DOD to replan the remainder of the Fishbowl series. The Urraca event was canceled to avoid further damage to satellites and three new shots were added." A second launch pad

8228-465: The electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force ). These effects can be combined in a partial differential equation for the magnetic field called the magnetic induction equation , where u is the velocity of the fluid; B is the magnetic B-field; and η = 1/σμ is the magnetic diffusivity , which is the reciprocal of the product of

8349-429: The existence of the magnetic field as early as 3,700 million years ago. Starting in the late 1800s and throughout the 1900s and later, the overall geomagnetic field has become weaker; the present strong deterioration corresponds to a 10–15% decline and has accelerated since 2000; geomagnetic intensity has declined almost continuously from a maximum 35% above the modern value, from circa year 1 AD. The rate of decrease and

8470-589: The failure of a microwave repeating station on Kauai , which cut off the sturdy telephone system from the other Hawaiian islands. The radius for an effective satellite kill for the Compton radiation produced by such a nuclear weapon in space was determined to be roughly 80 kilometres (50 mi). Further testing to this end was carried out, and embodied in a Department of Defense program, Program 437 . . There are problems with nuclear weapons carried over to testing and deployment scenarios, however. Because of

8591-484: The first technical reports, "The visible phenomena due to the burst were widespread and quite intense; a very large area of the Pacific was illuminated by the auroral phenomena, from far south of the south magnetic conjugate area ( Tongatapu ) through the burst area to far north of the north conjugate area ( French Frigate Shoals ). ... At twilight after the burst, resonant scattering of light from lithium and other debris

8712-420: 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

8833-429: 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. The motion of

8954-601: The inclination. 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. 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

9075-428: The initial plan of Operation Fishbowl, the nuclear tests were to be Bluegill , Starfish and Urraca , in that order. If a test were to fail, the next attempt of the same test would be of the same name plus the word "prime." If Bluegill failed, the next attempt would be Bluegill Prime , and if Bluegill Prime failed, the next attempt would be Bluegill Double Prime , etc. The first planned test of Operation Fishbowl

9196-451: The intensity of the debris auroras is greatest in the 60 to 125 miles range. Remote conjugate beta auroras can occur if the detonation is above 25 miles, whereas debris auroras appear only if the detonation altitude is in excess of some 200 miles." Some of the charged particles traveling along the Earth's magnetic field lines cause auroras and other geophysical phenomena in the conjugate areas. Other charged particles are reflected back along

9317-554: 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. The intensity of the magnetic field is subject to change over time. A 2021 paleomagnetic study from the University of Liverpool contributed to a growing body of evidence that

9438-405: The interior. The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core. The mechanism by which the Earth generates a magnetic field is known as a geodynamo . 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

9559-588: The last atmospheric nuclear test conducted by the United States, as the Limited Test Ban Treaty came into effect shortly thereafter. The United States completed six high-altitude nuclear tests in 1958, but the high-altitude tests of that year raised a number of questions. According to U.S. Government Report ADA955694 on the first successful test of the Fishbowl series, "Previous high-altitude nuclear tests: Teak , Orange , and Yucca , plus

9680-414: The last few centuries. 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. At this rate of decrease, the field would be negligible in about 1600 years. However, this strength is about average for the last 7 thousand years, and the current rate of change is not unusual. A prominent feature in

9801-491: The late 1950s, that high-altitude nuclear tests produce a number of unique geophysical phenomena at the opposite end of the magnetic field line of the Earth's magnetic field . According to the standard reference book on nuclear weapon effects by the United States Department of Defense , "For the high-altitude tests conducted in 1958 and 1962 in the vicinity of Johnston Island, the charged particles entered

9922-528: The launch of the Thor missile carrying the nuclear warhead. Most of these smaller instrumentation rockets were launched just after the time of the launch of the main Thor missile carrying the warhead. In addition, a large number of rocket-borne instruments were launched from a firing area at Barking Sands , Kauai , in the Hawaiian Islands. A very large number of United States military ships and aircraft were operating in support of Starfish Prime in

10043-422: 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). The heat is generated by potential energy released by heavier materials sinking toward the core ( planetary differentiation , the iron catastrophe ) as well as decay of radioactive elements in

10164-487: The magnet is suspended so it can turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field (the place where the field is directed downward into the Earth). The positions of the magnetic poles can be defined in at least two ways: locally or globally. The local definition is the point where the magnetic field is vertical. This can be determined by measuring

10285-643: The magnetic field once shifted at a rate of up to 6° per day at some time in Earth's history, a surprising result. However, in 2014 one of the original authors published a new study which found the results were actually due to the continuous thermal demagnitization of the lava, not to a shift in the magnetic field. In July 2020 scientists report that analysis of simulations and a recent observational field model show that maximum rates of directional change of Earth's magnetic field reached ~10° per year – almost 100 times faster than current changes and 10 times faster than previously thought. Although generally Earth's field

10406-467: 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 . 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. The animation shows how global declinations have changed over

10527-484: 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. There are also two concentric tire-shaped regions, called the Van Allen radiation belts , with high-energy ions (energies from 0.1 to 10  MeV ). The inner belt

10648-404: The missile with its warhead to be destroyed. No nuclear detonation occurred and no data was obtained, but subsequent investigation found that the Thor was actually following the proper flight trajectory. The second planned test of Operation Fishbowl was on June 19, 1962. The launch of a Thor missile with a nuclear warhead occurred just before midnight from Johnston Island. The Thor missile flew

10769-704: The non-dipolar part of the secular variation is a westward drift at a rate of about 0.2° per year. 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. 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. A 1995 study of lava flows on Steens Mountain , Oregon appeared to suggest

10890-519: The north pole of Earth's magnetic field (because opposite magnetic poles attract and the north end of a magnet, like a compass needle, points toward Earth's South magnetic field. While the North and South magnetic poles are usually located near the geographic poles, they slowly and continuously move over geological time scales, but sufficiently slowly for ordinary compasses to remain useful for navigation. However, at irregular intervals averaging several hundred thousand years, Earth's field reverses and

11011-435: 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. Historically, the north and south poles of a magnet were first defined by the Earth's magnetic field, not vice versa, since one of the first uses for a magnet was as a compass needle. A magnet's North pole is defined as the pole that is attracted by the Earth's North Magnetic Pole when

11132-486: 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 . An isoclinic chart (map of inclination contours) for the Earth's magnetic field

11253-402: The ocean in the vicinity of the island. Navy Explosive Ordnance Disposal and Underwater Demolition Team swimmers recovered approximately 250 pieces of the missile assembly during the next two weeks. Some of the debris was contaminated with plutonium . Nonessential personnel had been evacuated from Johnston Island during the test. On July 9, 1962, at 09:00:09 Coordinated Universal Time , which

11374-542: The other Fishbowl tests, a number of small rockets with various scientific instrumentation were launched from Johnson Island to monitor the effects of the high-altitude explosion. In the case of the Kingfish test, 29 rockets were launched from Johnston Island in addition to the Thor rocket carrying the nuclear warhead. According to the official report, at the time of the Kingfish detonation, "Johnston Island observers saw

11495-446: The ozone layer that protects the Earth from harmful ultraviolet radiation. One stripping mechanism is for gas to be caught in bubbles of the magnetic field, which are ripped off by solar winds. 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 . The study of

11616-418: 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. The Earth's magnetic north pole is drifting from northern Canada towards Siberia with

11737-422: The past magnetic field of the Earth is known as paleomagnetism. 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 paleomagnetism to track the past motion of continents. Reversals also provide

11858-417: 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. 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 . The motion of

11979-415: 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. Radiometric dating of lava flows has been used to establish a geomagnetic polarity time scale , part of which

12100-411: The rotational axis of the Earth. The dipole is roughly equivalent to a powerful bar magnet , with its south pole pointing towards the geomagnetic North Pole. 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

12221-447: The satellite damage caused by the Starfish Prime artificial radiation belts as well as other historical nuclear events that caused artificial radiation belts and their effects on many satellites that were then in orbit. The same report also projects the effects of one or more present-day high altitude nuclear explosions upon the formation of artificial radiation belts and the probable resulting effects on satellites that were in orbit as of

12342-411: The solar wind would have had a magnetic field orders of magnitude larger than the present solar wind. 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

12463-410: The southwest of Johnston Island so that the detonations would be farther from Hawaii. Urraca was to be a test of about 1 megaton yield at very high altitude (above 1000 km). The proposed Urraca test was always controversial, especially after the damage caused to satellites by the Starfish Prime detonation, as described below. Urraca was finally canceled, and an extensive re-evaluation of

12584-535: The three ARGUS shots were poorly instrumented and hastily executed. Despite thorough studies of the meager data, present models of these bursts are sketchy and tentative. These models are too uncertain to permit extrapolation to other altitudes and yields with any confidence. Thus there is a strong need, not only for better instrumentation, but for further tests covering a range of altitudes and yields." There were three phenomena in particular that required further investigation: The Fishbowl tests were monitored by

12705-593: The triggering of surge arresters on an airplane with a trailing-wire antenna during Starfish, Checkmate, and Bluegill; and the Oahu streetlight incident." (The "Oahu streetlight incident" refers to the 300 streetlights in Honolulu extinguished by the Starfish Prime detonation.) The final test of Operation Fishbowl was detonated at 2130 (9:30 p.m. local Johnston Island time) on November 3, 1962 (the time and date

12826-508: The very large radius associated with nuclear events, it was nearly impossible to prevent indiscriminate damage to other satellites, including one's own satellites. Starfish Prime produced an artificial radiation belt in space that soon destroyed three satellites ( Ariel , TRAAC , and Transit 4B all failed after traversing the radiation belt, while Cosmos V , Injun I and Telstar 1 suffered minor degradation, due to some radiation damage to solar cells , etc.). The radiation dose rate

12947-415: The very narrow range of 1.4 to 1.45 megatons (6.0 PJ). The Thor missile carrying the Starfish Prime warhead actually reached an apogee (maximum height) of about 1100 km (just over 680 miles), and the warhead was detonated on its downward trajectory when it had fallen to the programmed altitude of 400 kilometres (250 mi). The nuclear warhead detonated at 13 minutes and 41 seconds after liftoff of

13068-485: The year 2010. On July 25, 1962, a second attempt was made to launch the Bluegill device, but ended in disaster when the Thor suffered a stuck valve preventing the flow of LOX to the combustion chamber. The engine lost thrust and unburned RP-1 spilled down into the hot thrust chamber, igniting and starting a fire around the base of the missile. With the Thor engulfed in flames, the Range Safety Officer sent

13189-462: Was at least 0.6 Gy /day at four months after Starfish for a well-shielded satellite or crewed capsule in a polar circular earth orbit , which caused NASA concern with regard to its crewed space exploration programs. In general, nuclear effects in space (or very high altitudes) have a qualitatively different display. While an atmospheric nuclear explosion has a characteristic mushroom-shaped cloud , high-altitude and space explosions tend to manifest

13310-451: Was constructed during the operations pause so that Operation Fishbowl could continue in the event of another serious incident. After a pause of nearly three months, Operation Fishbowl was ready to continue, beginning with another attempt at the Bluegill test. Eighty-two days after the failure of Bluegill Prime , about 30 minutes before midnight on the night of October 15, 1962, local Johnston Island time (October 16 UTC ), another attempt

13431-431: Was delayed until June. Planning for Operation Fishbowl, as well as many other nuclear tests in the region, began rapidly in response to the sudden Soviet announcement on August 30, 1961, that they were ending a three-year moratorium on nuclear testing. The rapid planning of very complex operations necessitated many changes as the project progressed. All of the tests were to be launched on missiles from Johnston Island in

13552-406: Was incapacitated." There had been concern that eyeburn problems might occur during the earlier Starfish Prime test, since the countdown was rebroadcast by radio stations in Hawaii, and many civilians would be watching the thermonuclear detonation as it occurred, but no such problems in Hawaii were reported. The Kingfish detonation occurred at 0210 (Johnston Island time) on November 1, 1962, and

13673-485: Was made at the Bluegill test. The Thor missile malfunctioned and began tumbling out of control about 85 seconds after launch, and the range safety officer ordered the destruction of the missile and its nuclear warhead about 95 seconds after launch. On October 19, 1962, at about 90 minutes before midnight (local Johnston Island time), an XM-33 Strypi rocket launched a low-yield nuclear warhead which detonated successfully at an altitude of 147 kilometres (91 mi). It

13794-454: Was motivated by fears that the flash from the nighttime high-altitude detonations might blind civilians who were living on nearby islands. Johnston Island was a remote location, more distant from populated areas than other potential test locations. To protect residents of the Hawaiian Islands from flash blindness or permanent retinal injury from the bright nuclear flash, the nuclear missiles of Operation Fishbowl were launched generally toward

13915-482: Was nine seconds after 10 p.m. on July 8, Johnston Island local time, the Starfish Prime test was successfully detonated at an altitude of 400 kilometres (250 mi). The coordinates of the detonation were 16 degrees, 28 minutes North latitude, 169 degrees, 38 minutes West longitude (30 km, or about 18 mi, southwest of Johnston Island). The actual weapon yield was very close to the design yield, which has been described by various sources at different values in

14036-554: Was observed and after about 10 seconds a great white ball appeared to rise slowly out of the sea and was visible for about 9 minutes." After most of the electromagnetic pulse measurements on Starfish Prime had failed because the EMP was so much larger than expected, extra care was taken to obtain accurate EMP measurements on the Bluegill Triple Prime and Kingfish tests. The EMP mechanism that had been hypothesized before Operation Fishbowl had been conclusively disproven by

14157-551: Was observed at Johnston and French Frigate Shoals for many days confirming the longtime presence of debris in the atmosphere. An interesting side effect was that the Royal New Zealand Air Force was aided in anti-submarine maneuvers by the light from the bomb." The Starfish Prime radiation belt persisted at high altitude for many months and damaged the United States satellites Traac , Transit 4B , Injun I and Telstar I , as well as

14278-444: Was officially recorded as 0730 UTC , November 4, 1962). It was launched on a Nike-Hercules missile, and detonated at a lower altitude than the other Fishbowl tests. Although it was officially one of the Operation Fishbowl tests, it is sometimes not listed among high-altitude nuclear tests because of its lower detonation altitude. The nuclear yield was reported in most official documents only as being less than 20 kilotons. One report by

14399-460: Was on June 2, 1962, when a nuclear warhead was launched from Johnston Island on a Thor missile just after midnight. Although the Thor missile appeared to be on a normal trajectory, the radar tracking system lost track of the missile. Because of the large number of ships and aircraft in the area, there was no way to predict if the missile was on a safe trajectory, so the range safety officers ordered

14520-460: Was reported that the yield and burst altitude were very close to those desired, but according to most official documents the exact nuclear yield remains classified. It is reported in the open literature as simply being less than 20 kilotons. One report by the U.S. federal government, however, reported the Checkmate test yield as 10 kilotons. It was reported that, "Observers on Johnston Island saw

14641-419: Was the fourth successful detonation of the Fishbowl series. It was officially reported only as being a submegaton explosion (meaning in the range of more than 200 kilotons, but less than a megaton), but most independent observers believe that it used the same 400 kiloton warhead as the Bluegill Triple Prime test, although one report by the U.S. federal government reported the test yield as 200 kilotons. As with

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