|
Polar Drift
Polar drift is a geological phenomenon caused by variations in the flow of molten iron in Earth's outer core, resulting in changes in the orientation of Earth's magnetic field, and hence the position of the magnetic north- and south poles. The North magnetic pole is approximately from the geographic North Pole. The pole drifts considerably each day, which results in a change of 5-60 km per year. The speed of the change was around 10 km/year for the majority of the 20th century, then increased in the 1990s to over 50 km/year, but slowed down slightly after 2020. The South magnetic pole is constantly shifting due to changes in the Earth's magnetic field. it was calculated to lie at , placing it off the coast of Antarctica, between Adélie Land and Wilkes Land. In 2015, it lay at (est). That point lies outside the Antarctic Circle and it is moving northwest by about per year. Its current distance from the actual Geographic South Pole is approximately . The nearest permanen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic North Pole Positions 2015
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt, nickel, and their alloys. All substances exhibit some type of magnetism. Magnetic materials are classified according to their bulk susceptibility. Ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, but there are actually several types of magnetism. Paramagnetic substances, such as aluminium and oxygen, are weakly attracted to an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilkes Land
Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though this claim has been held in abeyance for the period of the operation of the Antarctic Treaty, to which Australia is a signatory. Geography Wilkes Land fronts on the southern Indian Ocean between Queen Mary Coast and Adélie Land, Adelie Land, extending from Cape Hordern in 100°31' E to Pourquoi Pas Point, in 136°11' E. The region extends as a Circular sector, sector about 2600 kilometre, km towards the South Pole, with an estimated land area of 2,600,000 km², mostly glaciated. Subdivisions It is further subdivided in the following coastal areas which can also be thought of as sectors extending to the South Pole: # Knox Coast: 100°31' E to 109°16' E # Budd Coast: 109°16' E to 115°33' E # Sabrina Coast: 115°33' E to 122°05' E # Banzare Coast: 122°05' E to 130°10' E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Wander
Polar wander is the motion of a pole in relation to some reference frame. It can be used, for example, to measure the degree to which Earth's magnetic poles have been observed to move relative to the Earth's rotation axis. It is also possible to use continents as reference and observe the relative motion of the magnetic pole relative to the different continents; by doing so, the relative motion of those two continents to each other can be observed over geologic time as paleomagnetism. Apparent polar wander The magnetic poles are relatively stationary in position over time and because of this, researchers often use magnetic minerals, like magnetite, in order to find at what latitude the continent was positioned relative to the magnetic poles of that time. Since the continents have been moving relative to the pole; it is as if they were immobile and the magnetic pole was moving instead. If enough data is collected, it is then possible to reconstruct the motion of the continents re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Reversal
A geomagnetic reversal is a change in the Earth's Dipole magnet, dipole magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with North Pole, geographic north and South Pole, geographic south). The Earth's magnetic field has alternated between periods of ''normal'' polarity, in which the predominant direction of the field was the same as the present direction, and ''reverse'' polarity, in which it was the opposite. These periods are called ''polarity chron, chrons''. Reversal occurrences appear to be statistically random. There have been at least 183 reversals over the last 83 million years (thus on average once every ~450,000 years). The latest, the Brunhes–Matuyama reversal, occurred 780,000 years ago with widely varying estimates of how quickly it happened. Some sources estimate the most recent four reversals took on average 7,000 years to occur. Clement (2004) suggests that this duration is dependent on latitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Excursion
A geomagnetic excursion, like a ''geomagnetic reversal'', is a significant change in the Earth's magnetic field. Unlike ''reversals'', an excursion is not a long-term re-orientation of the large-scale field, but rather represents a dramatic, typically a (geologically) short-lived change in field intensity, with a variation in pole orientation of up to 45° from the previous position. Excursion events typically only last a few thousand to a few tens of thousands of years, and often involve declines in field strength to between 0 and 20% of normal. Unlike full ''reversals'', ''excursions'' are generally not recorded around the entire globe. This is certainly due in part to them not registering well in the sedimentary record, but it also seems likely that excursions may not typically extend through the entire global geomagnetic field. There are significant exceptions, however. Occurrence Except for recent periods of the geologic past, it is not well known how frequently geomagnetic e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilkes Land Crater
Wilkes Land crater is an informal term that may apply to two separate cases of conjectured giant impact craters hidden beneath the ice cap of Wilkes Land, East Antarctica. These are distinguished by the names Wilkes Land anomaly and Wilkes Land mascon (mass concentration), based on terms used in their principal published reference sources. Wilkes Land anomaly A giant impact crater beneath the Wilkes Land ice sheet was first proposed by Richard A. Schmidt in 1962 on the basis of the seismic and gravity discovery of the feature made by the U.S. Victoria Land Traverse in 1959–60 (VLT), and the data provided to Schmidt by John G. Weihaupt, geophysicist of the VLT (Geophysical Studies in Victoria Land, Antarctica, Report No. 1, Geophysical and Polar Research Center, University of Wisconsin, 1–123). Schmidt further considered the possibility that it might be the elusive source of the tektites of the Australasian strewnfield (which is only 790,000 years old). The hypothesis was deta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dumont D'Urville Station
The Dumont d'Urville Station () is a French scientific station in Antarctica on Île des Pétrels, Géologie Archipelago, archipelago of Pointe-Géologie in Adélie Land. It is named after exploration, explorer Jules Dumont d'Urville, whose expedition landed on Débarquement Rock in the Dumoulin Islands at the northeast end of the archipelago on January 21, 1840. It is operated by the "French Polar Institute, French Polar Institute Paul-Émile Victor", a joint operation of French public and para-public agencies. It is the administrative centre of Adélie Land. History A pioneering French Antarctic research station, Port Martin, located east of D'Urville, was destroyed by fire on the night of January 23, 1952, without death or injury. In 1952, a small base was built on Île des Pétrels to study a rookery of emperor penguins. This base was called Base Marret. As the main base Port Martin was a total loss, Base Marret was chosen as overwintering site for 1952/1953. The new main b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the point in the Southern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True South Pole to distinguish from the south magnetic pole. The South Pole is by definition the southernmost point on the Earth, lying antipode (geography), antipodally to the North Pole. It defines geodetic latitude 90° South, as well as the direction of true south. At the South Pole all directions point North; all lines of longitude converge there, so its longitude can be defined as any degree value. No time zone has been assigned to the South Pole, so any time can be used as the local time. Along tight latitude circles, clockwise is east and counterclockwise is west. The South Pole is at the center of the Southern Hemisphere. Situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Circle
The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of Earth. The region south of this circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. South of the Antarctic Circle, the Sun is above the horizon for 24 continuous hours at least once per year (and therefore visible at solar midnight) and the centre of the Sun (ignoring refraction) is below the horizon for 24 continuous hours at least once per year (and therefore not visible at solar noon); this is also true within the Arctic Circle, the Antarctic Circle’s counterpart in the Northern Hemisphere. The position of the Antarctic Circle is not fixed and, not taking account of the nutation, currently runs south of the Equator. This figure may be slightly inaccurate because it does not allow for the effects of astronomical nutation, which can be up to 10″. Its latitude depends on the Earth's axial tilt, which fluctuates within ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adélie Land
Adélie Land ( ) or Adélie Coast is a Territorial claims in Antarctica, claimed territory of France located on the continent of Antarctica. It stretches from a portion of the Southern Ocean coastline all the way inland to the South Pole. France has administered it as one of five districts of the French Southern and Antarctic Lands since 1955 and applied the Antarctic Treaty System rules since 1961. Article 4 of the Antarctic Treaty deals with territorial claims, and although it does not renounce or diminish any preexisting claims to sovereignty, it also does not prejudice the position of contracting parties in their recognition or non-recognition of territorial sovereignty. France has had a permanent station in Adélie Land since 9 April 1950. Geography Adélie Land lies between 136th meridian east, 136° E (near Pourquoi Pas Point at ) and 142nd meridian east, 142° E (near Point Alden at ), with a shore length of about and with its inland part extending as a sector of a ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching , about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGDC
The United States National Geophysical Data Center (NGDC) provided scientific stewardship, products and services for geophysical data describing the solid earth, marine, and solar-terrestrial environment, as well as earth observations from space. It was established in 1965 as part of the new Environmental Science Services Administration until that organization became the National Oceanic & Atmospheric Administration (NOAA) in 1970. In 2015, NGDC was merged with the National Climatic Data Center (NCDC) and the National Oceanographic Data Center (NODC) into the National Centers for Environmental Information (NCEI). Location and controlling bodies Since 1972 the NGDC was located in Boulder, Colorado as a part of the US Department of Commerce (USDOC), National Oceanic & Atmospheric Administration (NOAA), National Environmental Satellite, Data and Information Service (NESDIS). Data holdings NGDC's data holdings contained more than 300 digital and analog databases, with over 37 terab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
