1.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
Geographic coordinate system
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Longitude lines are perpendicular and latitude lines are parallel to the equator.
2.
Apollo 17
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Apollo 17 was the final mission of NASAs Apollo program, the enterprise that landed the first humans on the Moon. Apollo 17 was the first night launch of a U. S. human spaceflight and it was a J-type mission which included three days on the lunar surface, extended scientific capability, and the third Lunar Roving Vehicle. Evans took scientific measurements and photographs from orbit using a Scientific Instruments Module mounted in the Service Module, Cernan, Evans and Schmitt returned to Earth on December 19 after a 12-day mission. Apollo 17 is the most recent manned Moon landing and was the last time humans travelled beyond low Earth orbit, the mission broke several records, the longest moon landing, longest total extravehicular activities, largest lunar sample, and longest time in lunar orbit. Eugene Cernan, Ronald Evans, and former X-15 pilot Joe Engle were assigned to the crew of Apollo 14. Engle flew sixteen X-15 flights, three of which exceeded the 50 mi border of space, following the rotation pattern that a backup crew would fly as the prime crew three missions later, Cernan, Evans, and Engle would have flown Apollo 17. Harrison Schmitt served on the crew of Apollo 15 and. However, Apollo 18 was cancelled in September 1970, following this decision, the scientific community pressured NASA to assign a geologist to an Apollo landing, as opposed to a pilot trained in geology. In light of pressure, Harrison Schmitt, a professional geologist, was assigned the Lunar Module Pilot position on Apollo 17. Scientist-astronaut Curt Michel believed that it was his own decision to resign, after it became clear that he would not be given a flight assignment, that mobilized this action. Subsequent to the decision to assign Schmitt to Apollo 17, there remained the question of which crew would become prime crew of the mission. NASA Director of Flight Crew Operations Deke Slayton ultimately assigned the crew of Apollo 14, along with Schmitt. The Apollo 15 prime crew received the backup assignment since this was to be the last lunar mission, however, when the Apollo 15 postage stamp incident became public in early 1972 the crew was reprimanded by NASA and the United States Air Force. Robert F. Overmyer Robert A. Parker C, three white stars above the red bars represent the three crewmen of the mission. The background includes the Moon, the planet Saturn and a galaxy or nebula, the wing of the eagle partially overlays the Moon, suggesting mans established presence there. The gaze of Apollo and the direction of the eagles motion embody mans intention to further destinations in space. The patch includes, along with the colors of the U. S. flag, the image of Apollo in the mission insignia is a rendering of the Apollo Belvedere sculpture. The insignia was designed by Robert McCall, with input from the crew, since Apollo 17 was to be the final lunar landing of the Apollo program, high-priority landing sites that had not been visited previously were given consideration for potential exploration
Apollo 17
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Gene Cernan aboard the Lunar Rover during the first EVA of Apollo 17
Apollo 17
Apollo 17
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Apollo 17 space-flown silver
Robbins medallion
Apollo 17
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Gene Cernan participates in geology training in
Sudbury, Ontario in May 1972
3.
The Blue Marble
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The Blue Marble is an image of the Earth made on December 7,1972, by the crew of the Apollo 17 spacecraft at a distance of about 45,000 kilometers. It is one of the most reproduced images in human history, the image with the official NASA designation AS17-148-22727 reproduces the view of the Earth as seen by the Apollo crew traveling toward the Moon. The translunar coast photograph extends from the Mediterranean Sea to Antarctica and this was the first time the Apollo trajectory made it possible to photograph the south polar ice cap, despite the Southern Hemisphere being heavily covered in clouds. In addition to the Arabian Peninsula and Madagascar, almost the entire coastline of Africa is clearly visible, the Asian mainland is on the horizon. The photograph, taken by astronauts on December 7,1972, EST, is one of the most widely distributed photographic images in existence. The image is one of the few to show an almost fully illuminated Earth disk, to the astronauts, the slightly gibbous Earth had the appearance and size of a glass marble, hence the name. The time of Apollo 17s launch,12,33 a. m, EST, meant that Africa was in daylight during the early hours of the spacecrafts flight. With the December solstice approaching, Antarctica was also illuminated, the 1972 Tamil Nadu cyclone can be seen in the top right of the image. This storm had brought flooding and high winds to the Indian state of Tamil Nadu on December 5, the photographs official NASA designation is AS17-148-22727. NASA photograph AS17-148-22726, taken just before and nearly identical to 22727, is used as a full-Earth image. The photographer used a 70-millimeter Hasselblad camera with an 80-millimeter Zeiss lens, Apollo 17 was the last manned lunar mission. No human since has been far enough from Earth to photograph an image such as The Blue Marble. The Blue Marble was not the first clear image taken of a face of the Earth. NASA archivist Mike Gentry has speculated that The Blue Marble is among the most widely distributed images in human history, there has also been a childrens television program called Big Blue Marble. The data also included a similarly manually assembled cloud-cover and night-lights image sets, a subsequent release was made in 2005, named Blue Marble Next Generation. A number of viewers for these data have also been released. On 25 January 2012, NASA released an image of the western hemisphere of Earth entitled Blue Marble 2012. The picture logged over 3.1 million views on the Flickr image hosting website within the first week of release
The Blue Marble
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The Blue Marble —Earth seen by Apollo 17 in 1972
The Blue Marble
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Blue Marble composite images generated by NASA in 2001 and 2002.
The Blue Marble
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"Blue Marble 2012" – a composite satellite image
The Blue Marble
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"Black Marble" – North and South America at night
4.
Antarctica
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It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, vegetation, where it occurs, is tundra. The continent, however, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources. In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north. For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
Antarctica
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Adelie penguins in Antarctica
Antarctica
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Antarctica
Antarctica
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Painting of
James Weddell 's second expedition in 1823, depicting the brig Jane and the cutter Beaufroy.
Antarctica
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Nimrod Expedition South Pole Party (left to right):
Wild,
Shackleton,
Marshall and
Adams
5.
South Pole
–
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earths axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth, situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year. The Geographic South Pole should not be confused with the South Magnetic Pole, the South Pole is at the center of the Southern Hemisphere. For most purposes, the Geographic South Pole is defined as the point of the two points where the Earths axis of rotation intersects its surface. However, the Earths axis of rotation is actually subject to very small wobbles, the geographic coordinates of the South Pole are usually given simply as 90°S, since its longitude is geometrically undefined and irrelevant. When a longitude is desired, it may be given as 0°, at the South Pole, all directions face north. For this reason, directions at the Pole are given relative to grid north, along tight latitude circles, clockwise is east, and counterclockwise is west, opposite to the North Pole. The Geographic South Pole is located on the continent of Antarctica. It sits atop a featureless, barren, windswept and icy plateau at an altitude of 2,835 metres above sea level, and is located about 1,300 km from the nearest open sea at Bay of Whales. The ice is estimated to be about 2,700 metres thick at the Pole, the polar ice sheet is moving at a rate of roughly 10 metres per year in a direction between 37° and 40° west of grid north, down towards the Weddell Sea. Therefore, the position of the station and other artificial features relative to the geographic pole gradually shift over time. The Geographic South Pole is marked by a stake in the ice alongside a small sign, these are repositioned each year in a ceremony on New Years Day to compensate for the movement of the ice. The sign records the respective dates that Roald Amundsen and Robert F. Scott reached the Pole, followed by a quotation from each man. A new marker stake is designed and fabricated each year by staff at the site, the Ceremonial South Pole is an area set aside for photo opportunities at the South Pole Station. It is located around 180 metres from the Geographic South Pole, Amundsens Tent, The tent was erected by the Norwegian expedition led by Roald Amundsen on its arrival on 14 December 1911. It is currently buried beneath the snow and ice in the vicinity of the Pole and it has been designated a Historic Site or Monument, following a proposal by Norway to the Antarctic Treaty Consultative Meeting. In 1820, several expeditions claimed to have been the first to have sighted Antarctica, with the very first being the Russian expedition led by Faddey Bellingshausen and Mikhail Lazarev. The first landing was probably just over a year later when American Captain John Davis, the basic geography of the Antarctic coastline was not understood until the mid-to-late 19th century
South Pole
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The Geographic South Pole. (The flag used on the flagpole is interchangeable.)
South Pole
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1. South Geographic Pole 2.
South Magnetic Pole (2007) 3.
South Geomagnetic Pole (2005) 4.
South Pole of Inaccessibility
South Pole
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The Ceremonial South Pole in 1998. (Background structures shown have since been replaced or altered.)
South Pole
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Argentine soldiers saluting the flag after erecting the pole in 1965
6.
Sphere
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A sphere is a perfectly round geometrical object in three-dimensional space that is the surface of a completely round ball. This distance r is the radius of the ball, and the point is the center of the mathematical ball. The longest straight line through the ball, connecting two points of the sphere, passes through the center and its length is twice the radius. While outside mathematics the terms sphere and ball are used interchangeably. The ball and the share the same radius, diameter. The surface area of a sphere is, A =4 π r 2, at any given radius r, the incremental volume equals the product of the surface area at radius r and the thickness of a shell, δ V ≈ A ⋅ δ r. The total volume is the summation of all volumes, V ≈ ∑ A ⋅ δ r. In the limit as δr approaches zero this equation becomes, V = ∫0 r A d r ′, substitute V,43 π r 3 = ∫0 r A d r ′. Differentiating both sides of equation with respect to r yields A as a function of r,4 π r 2 = A. Which is generally abbreviated as, A =4 π r 2, alternatively, the area element on the sphere is given in spherical coordinates by dA = r2 sin θ dθ dφ. In Cartesian coordinates, the element is d S = r r 2 − ∑ i ≠ k x i 2 ∏ i ≠ k d x i, ∀ k. For more generality, see area element, the total area can thus be obtained by integration, A = ∫02 π ∫0 π r 2 sin θ d θ d φ =4 π r 2. In three dimensions, the volume inside a sphere is derived to be V =43 π r 3 where r is the radius of the sphere, archimedes first derived this formula, which shows that the volume inside a sphere is 2/3 that of a circumscribed cylinder. In modern mathematics, this formula can be derived using integral calculus, at any given x, the incremental volume equals the product of the cross-sectional area of the disk at x and its thickness, δ V ≈ π y 2 ⋅ δ x. The total volume is the summation of all volumes, V ≈ ∑ π y 2 ⋅ δ x. In the limit as δx approaches zero this equation becomes, V = ∫ − r r π y 2 d x. At any given x, a right-angled triangle connects x, y and r to the origin, hence, applying the Pythagorean theorem yields, thus, substituting y with a function of x gives, V = ∫ − r r π d x. Which can now be evaluated as follows, V = π − r r = π − π =43 π r 3
Sphere
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Circumscribed cylinder to a sphere
Sphere
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A two-dimensional
perspective projection of a sphere
Sphere
Sphere
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Deck of playing cards illustrating engineering instruments, England, 1702.
King of spades: Spheres
7.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
Earth
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"
The Blue Marble " photograph of Earth, taken during the
Apollo 17 lunar mission in 1972
Earth
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Artist's impression of the early Solar System's planetary disk
Earth
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World map color-coded by relative height
Earth
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The summit of
Chimborazo, in Ecuador, is the point on Earth's surface farthest from its center.
8.
Equator
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The Equator usually refers to an imaginary line on the Earths surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere. The Equator is about 40,075 kilometres long, some 78. 7% lies across water and 21. 3% over land, other planets and astronomical bodies have equators similarly defined. Generally, an equator is the intersection of the surface of a sphere with the plane that is perpendicular to the spheres axis of rotation. The latitude of the Earths equator is by definition 0° of arc, the equator is the only line of latitude which is also a great circle — that is, one whose plane passes through the center of the globe. The plane of Earths equator when projected outwards to the celestial sphere defines the celestial equator, in the cycle of Earths seasons, the plane of the equator passes through the Sun twice per year, at the March and September equinoxes. To an observer on the Earth, the Sun appears to travel North or South over the equator at these times, light rays from the center of the Sun are perpendicular to the surface of the Earth at the point of solar noon on the Equator. Locations on the Equator experience the quickest sunrises and sunsets because the sun moves nearly perpendicular to the horizon for most of the year. The Earth bulges slightly at the Equator, the diameter of the Earth is 12,750 kilometres. Because the Earth spins to the east, spacecraft must also launch to the east to take advantage of this Earth-boost of speed, seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earths axis relative to the plane of revolution. During the year the northern and southern hemispheres are inclined toward or away from the sun according to Earths position in its orbit, the hemisphere inclined toward the sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter. At the equinoxes, the Earths axis is not tilted toward the sun, instead it is perpendicular to the sun meaning that the day is about 12 hours long, as is the night, across the whole of the Earth. Near the Equator there is distinction between summer, winter, autumn, or spring. The temperatures are usually high year-round—with the exception of high mountains in South America, the temperature at the Equator can plummet during rainstorms. In many tropical regions people identify two seasons, the wet season and the dry season, but many places close to the Equator are on the oceans or rainy throughout the year, the seasons can vary depending on elevation and proximity to an ocean. The Equator lies mostly on the three largest oceans, the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean. The highest point on the Equator is at the elevation of 4,690 metres, at 0°0′0″N 77°59′31″W and this is slightly above the snow line, and is the only place on the Equator where snow lies on the ground. At the Equator the snow line is around 1,000 metres lower than on Mount Everest, the Equator traverses the land of 11 countries, it also passes through two island nations, though without making a landfall in either. Starting at the Prime Meridian and heading eastwards, the Equator passes through, Despite its name, however, its island of Annobón is 155 km south of the Equator, and the rest of the country lies to the north
Equator
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Left: A monument marking the Equator near the town of
Pontianak, Indonesia Right: Road sign marking the Equator near
Nanyuki, Kenya
Equator
Equator
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The Equator marked as it crosses
Ilhéu das Rolas, in São Tomé and Príncipe
9.
Continent
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A continent is one of several very large landmasses on Earth. Generally identified by convention rather than any strict criteria, up to seven regions are regarded as continents. Ordered from largest in size to smallest, they are, Asia, Africa, North America, South America, Antarctica, Europe, in geology, areas of continental crust include regions covered with water. Islands are frequently grouped with a continent to divide all the worlds land into geopolitical regions. Under this scheme, most of the countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form a geopolitical region called Oceania. By convention, continents are understood to be large, continuous, discrete masses of land, many of the seven most commonly recognized continents identified by convention are not discrete landmasses separated completely by water. Earths major landmasses all have coasts on a single, continuous World Ocean, the most restricted meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. From this perspective the edge of the shelf is the true edge of the continent. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia, as a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered part of Europe and Madagascar part of Africa, extrapolating the concept to its extreme, some geographers group the Australasian continental plate with other islands in the Pacific into one continent called Oceania. This divides the land surface of Earth into continents or quasi-continents. The ideal criterion that each continent be a discrete landmass is commonly relaxed due to historical conventions, of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by ocean. Several continents are defined not as absolutely distinct bodies but as more or less discrete masses of land, Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama. In both cases, there is no separation of these landmasses by water. Both these isthmuses are very narrow compared to the bulk off the landmasses they unite, North America and South America are treated as separate continents in the seven-continent model. However, they may also be viewed as a continent known as America or the Americas. This viewpoint was common in the United States until World War II and this remains the more common vision in Latin American countries, Spain, Portugal, France, Italy and Greece, where they are taught as a single continent. The criterion of a landmass is completely disregarded if the continuous landmass of Eurasia is classified as two separate continents, Europe and Asia
Continent
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The Ancient Greek geographer
Strabo holding a globe showing Europa and Asia
Continent
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Animated, color-coded map showing the various continents and regions.
Depending on the convention and model, some continents may be consolidated or subdivided: for example,
Eurasia is most often subdivided into
Europe and
Asia (red shades), while
North and
South America are sometimes recognized as
one American continent (green shades).
Continent
–
Medieval
T and O map showing the three continents as domains of the sons of
Noah —Asia to Sem (
Shem), Europe to Iafeth (
Japheth), and Africa to Cham (
Ham).
Continent
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Universalis Cosmographia, Waldseemüller's 1507 world map—the first to show the Americas separate from Asia
10.
Australia (continent)
–
It is the smallest of the seven traditional continents in the English conception. When sea levels were lower during the Pleistocene ice age, including the Last Glacial Maximum about 18,000 BC, geologically, a continent extends to the edge of its continental shelf, so the now-separate islands are considered part of the continent. Due to the spread of animals, fungi and plants across the single Pleistocene landmass the separate lands have a related biota, New Zealand is not part of the continent of Australia, but of the separate, submerged continent of Zealandia. New Zealand and Australia are both part of the regions known as Australasia and Oceania. The term Oceania is often used to denote the region encompassing the Australian continent, with a total land area of 8.56 million square kilometres, the Australian continent is the smallest and lowest human inhabited continent on Earth. The continental shelf connecting the islands, half of which is less than 50 metres deep, covers some 2.5 million square kilometres, including the Sahul Shelf and Bass Strait. As the country of Australia is mostly on a single landmass, archaeological terminology for this region has changed repeatedly. In the early 1970s, the term Greater Australia was introduced for the Pleistocene continent, then at a 1975 conference and consequent publication, the name Sahul was extended from its previous use for just the Sahul Shelf to cover the continent. Others have used Meganesia with different meanings, travel writer Paul Theroux included New Zealand in his definition and others have used it for Australia, New Zealand, another biologist, Richard Dawkins, coined the name Australinea in 2004. Australia-New Guinea has also been used, the continent primarily sits on the Indo-Australian Plate. Because of its location on its tectonic plate Australia doesnt have any active volcanic regions. The lands were joined with Antarctica as part of the southern supercontinent Gondwana until the plate began to drift north about 96 million years ago, for most of the time since then, Australia–New Guinea remained a continuous landmass. When the last glacial period ended in about 10,000 BC, rising sea levels formed Bass Strait, separating Tasmania from the mainland. Then between about 8,000 and 6,500 BC, the lowlands in the north were flooded by the sea, separating New Guinea, the Aru Islands, and the Australian mainland. A northern arc consisting of the New Guinea Highlands, the Raja Ampat Islands, the Outer Banda Arc was accreted along the northwestern edge the continent, it includes the islands of Timor, Tanimbar, and Seram. As the continent drifted north from Antarctica, a fauna, flora. Marsupials and monotremes also existed on other continents, but only in Australia–New Guinea did they out-compete the placental mammals, animal groups such as macropods, monotremes, and cassowaries are endemic to Australia. There were three reasons for the enormous diversity that developed in animal, fungal and plant life
Australia (continent)
–
Mainland
Australia showing the continental
Sahul Shelf (light blue) extending to the islands of New Guinea in the north, the island of Timor in the northwest, and Tasmania in the south
Australia (continent)
–
Australia
11.
South America
–
South America is a continent located in the western hemisphere, mostly in the southern hemisphere, with a relatively small portion in the northern hemisphere. It may also be considered a subcontinent of the Americas, which is the used in nations that speak Romance languages. The reference to South America instead of other regions has increased in the last decades due to changing geopolitical dynamics. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean, North America and it includes twelve sovereign states, a part of France, and a non-sovereign area. In addition to this, the ABC islands of the Kingdom of the Netherlands, Trinidad and Tobago, South America has an area of 17,840,000 square kilometers. Its population as of 2005 has been estimated at more than 371,090,000, South America ranks fourth in area and fifth in population. Brazil is by far the most populous South American country, with more than half of the population, followed by Colombia, Argentina, Venezuela. In recent decades Brazil has also concentrated half of the regions GDP and has become a first regional power, most of the population lives near the continents western or eastern coasts while the interior and the far south are sparsely populated. Most of the continent lies in the tropics, the continents cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the majority of South Americans speak Portuguese or Spanish. South America occupies the portion of the Americas. The continent is delimited on the northwest by the Darién watershed along the Colombia–Panama border. Almost all of mainland South America sits on the South American Plate, South Americas major mineral resources are gold, silver, copper, iron ore, tin, and petroleum. These resources found in South America have brought high income to its countries especially in times of war or of rapid growth by industrialized countries elsewhere. However, the concentration in producing one major export commodity often has hindered the development of diversified economies and this is leading to efforts to diversify production to drive away from staying as economies dedicated to one major export. South America is one of the most biodiverse continents on earth, South America is home to many interesting and unique species of animals including the llama, anaconda, piranha, jaguar, vicuña, and tapir. The Amazon rainforests possess high biodiversity, containing a proportion of the Earths species. Brazil is the largest country in South America, encompassing around half of the land area
South America
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A composite relief image of South America.
South America
–
South America
South America
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Cuernos del Paine in Chile (left) and
Morro do Chapéu in Brazil (right) serve to illustrate the diversity of landscapes in South America. Click to enlarge.
South America
12.
Africa
–
Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities, cultures and languages. In the late 19th century European countries colonized most of Africa, Africa also varies greatly with regard to environments, economics, historical ties and government systems. However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which also included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2. Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
Africa
–
Map of Africa
Africa
–
Africa
Africa
–
Lucy, an
Australopithecus afarensis skeleton discovered on November 24, 1974, in the
Awash Valley of
Ethiopia 's
Afar Depression
Africa
–
Colossal statues of
Ramesses II at
Abu Simbel, Egypt, date from around 1400 BC.
13.
Asia
–
Asia covers an area of 44,579,000 square kilometres, about 30% of Earths total land area and 8. 7% of the Earths total surface area. The continent, which has long been home to the majority of the population, was the site of many of the first civilizations. Asia is notable for not only its large size and population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, the western boundary with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains, China and India alternated in being the largest economies in the world from 1 to 1800 A. D. The accidental discovery of America by Columbus in search for India demonstrates this deep fascination, the Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties, the boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia, the border between Asia and Europe was historically defined by European academics. In Sweden, five years after Peters death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia, the Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg, the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century, the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is usually placed along the crest of the Caucasus Mountains, the border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the possessions of the various empires there. Lewis and Wigen assert, The narrowing of Southeast Asia to its present boundaries was thus a gradual process, Asia is larger and more culturally diverse than Europe. It does not exactly correspond to the borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds there is no or is no substantial physical separation between them
Asia
–
Two-point equidistant projection of Asia and surrounding landmasses.
Asia
–
Asia
Asia
–
The racial diversity of Asia's peoples,
Nordisk familjebok (1904)
Asia
–
Ptolemy's Asia
14.
Ocean
–
An ocean is a body of saline water that composes much of a planets hydrosphere. On Earth, an ocean is one of the major divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern, the word sea is often used interchangeably with ocean in American English but, strictly speaking, a sea is a body of saline water partly or fully enclosed by land. The ocean contains 97% of Earths water, and oceanographers have stated that less than 5% of the World Ocean has been explored, the total volume is approximately 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the component of Earths hydrosphere, it is integral to all known life, forms part of the carbon cycle. The world ocean is the habitat of 230,000 known species, but because much of it is unexplored, the origin of Earths oceans remains unknown, oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds, the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many planets and natural satellites, notably. The Solar Systems giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of water within a circumstellar habitable zone. Ocean planets are a type of planet with a surface completely covered with liquid. The concept of Ōkeanós has an Indo-European connection, Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases, though generally described as several separate oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a body of water with relatively free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits. The Mid-Oceanic Ridge of the World are connected and form the Ocean Ridge, the continuous mountain range is 65,000 km long, and the total length of the oceanic ridge system is 80,000 km long
Ocean
–
Surface of the
Atlantic Ocean meeting
Earth 's
planetary boundary layer and
troposphere.
Ocean
–
Artist's conception of subsurface ocean of Enceladus confirmed April 3, 2014.
Ocean
–
Two models for the composition of Europa predict a large subsurface ocean of liquid water. Similar models have been proposed for other celestial bodies in the Solar System
Ocean
–
Diagram showing a possible internal structure of
Ceres
15.
Indian Ocean
–
The Indian Ocean is the third largest of the worlds oceanic divisions, covering 70,560,000 km2. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, the Indian Ocean is known as Ratnākara, the mine of gems in ancient Sanskrit literature, and as Hind Mahāsāgar, in Hindi. The northernmost extent of the Indian Ocean is approximately 30° north in the Persian Gulf, the oceans continental shelves are narrow, averaging 200 kilometres in width. An exception is found off Australias western coast, where the width exceeds 1,000 kilometres. The average depth of the ocean is 3,890 m and its deepest point is Diamantina Deep in Diamantina Trench, at 8,047 m deep, Sunda Trench has a depth of 7, 258–7,725 m. North of 50° south latitude, 86% of the basin is covered by pelagic sediments. The remaining 14% is layered with terrigenous sediments, glacial outwash dominates the extreme southern latitudes. The major choke points include Bab el Mandeb, Strait of Hormuz, the Lombok Strait, the Strait of Malacca, the Indian Ocean is artificially connected to the Mediterranean Sea through the Suez Canal, which is accessible via the Red Sea. All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere is in this ocean, marginal seas, gulfs, bays and straits of the Indian Ocean include, The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April, from May until October south, in the Arabian Sea the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are milder. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea, the Indian Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, Indian Ocean warming is the largest among the tropical oceans, and about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming, and changes in the frequency, among the few large rivers flowing into the Indian Ocean are the Zambezi, Shatt al-Arab, Indus, Godavari, Krishna, Narmada, Ganges, Brahmaputra, Jubba and Irrawaddy River. The oceans currents are controlled by the monsoon. Two large gyres, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, during the winter monsoon, however, currents in the north are reversed. Deep water circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, north of 20° south latitude the minimum surface temperature is 22 °C, exceeding 28 °C to the east. Southward of 40° south latitude, temperatures drop quickly, surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and south-western Australia
Indian Ocean
–
The economically important
Silk Road (red) and spice
trade routes (blue) were blocked by the
Ottoman Empire in ca. 1453 with the fall of the
Byzantine Empire. This spurred exploration, and a new sea route around Africa was found, triggering the
Age of Discovery.
Indian Ocean
–
Extent of the Indian Ocean according to the
CIA World Factbook
Indian Ocean
–
British heavy cruisers
Dorsetshire and
Cornwall under Japanese air attack and heavily damaged on 5 April 1942
Indian Ocean
–
A
dhow off the coast of Kenya
16.
Atlantic Ocean
–
The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa. The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays, gulfs, and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
Atlantic Ocean
–
The Atlantic Ocean as seen from the western coast of
Portugal
Atlantic Ocean
–
The Atlantic Ocean, not including
Arctic and
Antarctic regions
Atlantic Ocean
–
The Atlantic Ocean as seen from
Atlantic City, New Jersey.
Atlantic Ocean
–
Myrtle Beach, South Carolina view of the Atlantic Ocean.
17.
Southern Ocean
–
As such, it is regarded as the fourth-largest of the five principal oceanic divisions, smaller than the Pacific, Atlantic, and Indian Oceans but larger than the Arctic Ocean. This ocean zone is cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters. By way of his voyages in the 1770s, Captain James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Oceans northern boundary or even existence, considering the part of the Pacific, Atlantic. Others regard the seasonally-fluctuating Antarctic Convergence as the natural boundary, Borders and names for oceans and seas were internationally agreed when the International Hydrographic Bureau, the precusor to the IHO, convened the First International Conference on 24 July 1919. The IHO then published these in its Limits of Oceans and Seas, Australian authorities regard the Southern Ocean as lying immediately south of Australia. Map publishers using the term Southern Ocean on their maps include Hema Maps, Southern Ocean is an obsolete name for the Pacific Ocean or South Pacific, coined by Vasco Núñez de Balboa, the first European to discover it, who approached it from the north. The South Seas is an archaic synonym. A1745 British Act of Parliament established a prize for discovering a Northwest Passage to the Western and Southern Ocean of America, authors using Southern Ocean to name the waters encircling the unknown southern polar regions used varying limits. James Cooks account of his second voyage implies New Caledonia borders it, peacocks 1795 Geographical Dictionary said it lay to the southward of America and Africa, John Payne in 1796 used 40 degrees as the northern limit, the 1827 Edinburgh Gazetteer used 50 degrees. The United Kingdoms South Australia Act 1834 described the waters forming the southern limit of the new colony of South Australia as the Southern Ocean. The Colony of Victorias Legislative Council Act of 1881 delimited part of the division of Bairnsdale as along the New South Wales boundary to the Southern ocean. The limit then followed the west coast of Tasmania southwards to the South East Cape and then went eastwards to Broughton Island, New Zealand, the northern limits of the Southern Ocean were moved southwards in the IHOs 1937 second edition of the Limits of Oceans and Seas. From this edition, much of the northern limit ceased to abut land masses. As is discussed in detail below, prior to the 2002 edition the limits of oceans explicitly excluded the seas lying within each of them. The Great Australian Bight was unnamed in the 1928 edition, and it therefore encompassed former Southern Ocean waters but was technically not inside any of the three adjacent oceans by 1937. To perform direct comparisons of current and former limits of oceans it is necessary to consider, or at least be aware of, the limits of the Atlantic, Pacific and Indian Oceans have therefore been extended South to the Antarctic Continent. The IHO readdressed the question of the Southern Ocean in a survey in 2000, of its 68 member nations,28 responded, and all responding members except Argentina agreed to redefine the ocean, reflecting the importance placed by oceanographers on ocean currents
Southern Ocean
–
1928 First Edition of Limits of Oceans and Seas with original IHO delineation of Southern Ocean abutting land-masses.
Southern Ocean
–
Earth's oceans
Southern Ocean
–
1937 Second Edition of Limits of Oceans and Seas showing IHO's pre-1953 delineation of Southern Ocean moved southwards.
Southern Ocean
–
1564 Typus Orbis Terrarum, a map by
Abraham Ortelius showed the imagined link between the proposed continent of Antarctica and
South America.
18.
Pacific Ocean
–
The Pacific Ocean is the largest and deepest of the Earths oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west, the Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres. Both the center of the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean, the oceans current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means peaceful sea, important human migrations occurred in the Pacific in prehistoric times. Long-distance trade developed all along the coast from Mozambique to Japan, trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality, from 1404 to 1433 Zheng He led expeditions into the Indian Ocean. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and he named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. Later, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Castilian expedition of world circumnavigation starting in 1519, Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until the eighteenth century, sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, and Papua New Guinea. In 1542–43 the Portuguese also reached Japan, in 1564, five Spanish ships consisting of 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi and sailed to the Philippines and Mariana Islands. The Manila galleons operated for two and a half centuries linking Manila and Acapulco, in one of the longest trade routes in history, Spanish expeditions also discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, and the Admiralty Islands in the South Pacific. In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum—a sea closed to other naval powers, as the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines, Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska. The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest, one of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan, in Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888, by occupying Easter Island, Chile joined the imperial nations
Pacific Ocean
–
Maris Pacifici by
Ortelius (1589). One of the first printed maps to show the Pacific Ocean; see also
Waldseemüller map (1507).
Pacific Ocean
–
The Pacific Ocean
Pacific Ocean
–
USS
Lexington under air attack on 8 May 1942 during the
Battle of the Coral Sea
Pacific Ocean
–
Map of the Pacific Ocean during European Exploration, circa 1702–1707.
19.
Pacific Islands
–
The Pacific Islands is a term broadly referring to the islands of the Pacific Ocean. Depending on the context, it may refer to countries and islands with common Austronesian origins, islands once or currently colonized, in English, the umbrella term Pacific Islands may take on several meanings. Sometimes it refers to only those islands covered by the continent of Oceania, there are many other islands located within the boundaries of the Pacific Ocean that are not considered part of Oceania. This list includes all islands found in the geographic Pacific Ocean, with an area larger than 10,000 square kilometers
Pacific Islands
–
Pacific Islands leaders, all members of the
Pacific Islands Forum, at a meeting in
Samoa with US Secretary of State
Condoleezza Rice (center), 26 July 2008
Pacific Islands
–
Three of the major groups of islands in the
Pacific Ocean.
20.
Oceania
–
Oceania, also known as Oceanica, is a region centred on the islands of the tropical Pacific Ocean. The term is used more specifically to denote a continent comprising Australia. The term was coined as Océanie circa 1812 by geographer Conrad Malte-Brun, the word Océanie is a French word derived from the Latin word oceanus, and this from the Greek word ὠκεανός, ocean. Natives and inhabitants of this region are called Oceanians or Oceanicans, as an ecozone, Oceania includes all of Micronesia, Fiji, and all of Polynesia except New Zealand. New Zealand, along with New Guinea and nearby islands, part of the Philippine islands, Australia, the Solomon Islands, Vanuatu, in geopolitical terms, however, New Zealand, the Solomon Islands, Vanuatu and New Caledonia are almost always considered part of Oceania. Australia and Papua New Guinea are usually considered part of Oceania along with the Maluku Islands, puncak Jaya in Papua is often considered the highest peak in Oceania. Oceania was originally conceived as the lands of the Pacific Ocean and it comprised four regions, Polynesia, Micronesia, Malaysia, and Melanesia. The area extends to Sumatra in the west, the Bonin Islands in the northwest, the Hawaiian Islands in the northeast, Rapa Nui and Sala y Gómez Island in the east, and Macquarie Island in the south. Not included are the Pacific islands of Taiwan, the Ryukyu Islands and the Japanese archipelago, all on the margins of Asia, and the Aleutian Islands of North America. The islands at the extremes of Oceania are Bonin, a politically integral part of Japan, Hawaii, a state of the United States. There is also a geographic definition that excludes land on the Sunda Plate. Biogeographically, Oceania is used as a synonym for either the Australasian ecozone or the Pacific ecozone, Oceania is one of eight terrestrial ecozones, which constitute the major ecological regions of the planet. The Oceania ecozone includes all of Micronesia, Fiji, and all of Polynesia except New Zealand, New Zealand, New Guinea, Melanesia apart from Fiji, and Australia constitute the separate Australasian ecozone. The Malay Archipelago is part of the Indomalaya ecozone, related to these concepts are Near Oceania, that part of western Island Melanesia which has been inhabited for tens of millennia, and Remote Oceania which is more recently settled. The term is used to denote a continent comprising Australia. New Zealand forms the corner of the Polynesian Triangle. Its indigenous Māori constitute one of the cultures of Polynesia. It is also, however, considered part of Australasia, the history of Oceania in the medieval period was synonymous with the history of the indigenous peoples of Australasia, Micronesia, Melanesia, Polynesia
Oceania
–
A map of Oceania from the CIA World Factbook
Oceania
–
Geopolitical Oceania
Oceania
–
Aoraki / Mount Cook, located on the
South Island of
New Zealand
Oceania
–
Satellite image of Oceania
21.
Sun
–
The Sun is the star at the center of the Solar System. It is a perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99. 86% of the total mass of the Solar System. About three quarters of the Suns mass consists of hydrogen, the rest is mostly helium, with smaller quantities of heavier elements, including oxygen, carbon, neon. The Sun is a G-type main-sequence star based on its spectral class and it formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into a disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core and it is thought that almost all stars form by this process. The Sun is roughly middle-aged, it has not changed dramatically for more than four billion years and it is calculated that the Sun will become sufficiently large enough to engulf the current orbits of Mercury, Venus, and probably Earth. The enormous effect of the Sun on Earth has been recognized since prehistoric times, the synodic rotation of Earth and its orbit around the Sun are the basis of the solar calendar, which is the predominant calendar in use today. The English proper name Sun developed from Old English sunne and may be related to south, all Germanic terms for the Sun stem from Proto-Germanic *sunnōn. The English weekday name Sunday stems from Old English and is ultimately a result of a Germanic interpretation of Latin dies solis, the Latin name for the Sun, Sol, is not common in general English language use, the adjectival form is the related word solar. The term sol is used by planetary astronomers to refer to the duration of a solar day on another planet. A mean Earth solar day is approximately 24 hours, whereas a mean Martian sol is 24 hours,39 minutes, and 35.244 seconds. From at least the 4th Dynasty of Ancient Egypt, the Sun was worshipped as the god Ra, portrayed as a falcon-headed divinity surmounted by the solar disk, and surrounded by a serpent. In the New Empire period, the Sun became identified with the dung beetle, in the form of the Sun disc Aten, the Sun had a brief resurgence during the Amarna Period when it again became the preeminent, if not only, divinity for the Pharaoh Akhenaton. The Sun is viewed as a goddess in Germanic paganism, Sól/Sunna, in ancient Roman culture, Sunday was the day of the Sun god. It was adopted as the Sabbath day by Christians who did not have a Jewish background, the symbol of light was a pagan device adopted by Christians, and perhaps the most important one that did not come from Jewish traditions
Sun
–
The Sun in visible wavelength with filtered white light on 8 July 2014. Characteristic
limb darkening and numerous
sunspots are visible.
Sun
–
During a total
solar eclipse, the solar
corona can be seen with the naked eye, during the brief period of totality.
Sun
–
Taken by
Hinode 's Solar Optical Telescope on 12 January 2007, this image of the Sun reveals the filamentary nature of the plasma connecting regions of different magnetic polarity.
Sun
–
Visible light photograph of sunspot, 13 December 2006
22.
Ecliptic
–
The ecliptic is the apparent path of the Sun on the celestial sphere, and is the basis for the ecliptic coordinate system. It also refers to the plane of this path, which is coplanar with the orbit of Earth around the Sun, the motions as described above are simplifications. Due to the movement of Earth around the Earth–Moon center of mass, due to further perturbations by the other planets of the Solar System, the Earth–Moon barycenter wobbles slightly around a mean position in a complex fashion. The ecliptic is actually the apparent path of the Sun throughout the course of a year, because Earth takes one year to orbit the Sun, the apparent position of the Sun also takes the same length of time to make a complete circuit of the ecliptic. With slightly more than 365 days in one year, the Sun moves a little less than 1° eastward every day, again, this is a simplification, based on a hypothetical Earth that orbits at uniform speed around the Sun. The actual speed with which Earth orbits the Sun varies slightly during the year, for example, the Sun is north of the celestial equator for about 185 days of each year, and south of it for about 180 days. The variation of orbital speed accounts for part of the equation of time, if the equator is projected outward to the celestial sphere, forming the celestial equator, it crosses the ecliptic at two points known as the equinoxes. The Sun, in its apparent motion along the ecliptic, crosses the equator at these points, one from south to north. The crossing from south to north is known as the equinox, also known as the first point of Aries. The crossing from north to south is the equinox or descending node. Likewise, the ecliptic itself is not fixed, the gravitational perturbations of the other bodies of the Solar System cause a much smaller motion of the plane of Earths orbit, and hence of the ecliptic, known as planetary precession. The combined action of two motions is called general precession, and changes the position of the equinoxes by about 50 arc seconds per year. Once again, this is a simplification, periodic motions of the Moon and apparent periodic motions of the Sun cause short-term small-amplitude periodic oscillations of Earths axis, and hence the celestial equator, known as nutation. Obliquity of the ecliptic is the used by astronomers for the inclination of Earths equator with respect to the ecliptic. It is about 23. 4° and is currently decreasing 0.013 degrees per hundred years due to planetary perturbations, the angular value of the obliquity is found by observation of the motions of Earth and other planets over many years. From 1984, the Jet Propulsion Laboratorys DE series of computer-generated ephemerides took over as the ephemeris of the Astronomical Almanac. Obliquity based on DE200, which analyzed observations from 1911 to 1979, was calculated, jPLs fundamental ephemerides have been continually updated. J. Laskar computed an expression to order T10 good to 0″. 04/1000 years over 10,000 years, all of these expressions are for the mean obliquity, that is, without the nutation of the equator included
Ecliptic
Ecliptic
23.
Summer
–
Summer is the hottest of the four temperate seasons, falling between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, the date of the beginning of summer varies according to climate, tradition and culture. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, a variable seasonal lag means that the meteorological center of the season, which is based on average temperature patterns, occurs several weeks after the time of maximal insolation. Under meteorological definitions, all seasons are set to start at the beginning of a calendar month. This meteorological definition of summer also aligns with the commonly viewed notion of summer as the season with the longest days of the year, the meteorological reckoning of seasons is used in Australia, Austria, Denmark, the former Soviet Union and Japan. It is also used by many in the United Kingdom, in Ireland, the summer months according to the national meteorological service, Met Éireann, are June, July and August. However, according to the Irish Calendar, summer begins on 1 May, school textbooks in Ireland follow the cultural norm of summer commencing on 1 May rather than the meteorological definition of 1 June. Reckoning by hours of daylight alone, summer solstice marks the midpoint, not the beginning, midsummer takes place over the shortest night of the year, which is the summer solstice, or on a nearby date that varies with tradition. Where a seasonal lag of half a season or more is common, by this method, in North America, summer is the period from the summer solstice to the autumn equinox. The similar Canadian tradition starts summer on Victoria Day one week prior and ends, as in the United States, on Labour Day. In Chinese astronomy, summer starts on or around 5 May, with the known as lìxià, i. e. establishment of summer. In Australia and New Zealand, summer begins on 1 December. Summer is traditionally associated with hot or warm weather, in the Mediterranean regions, it is also associated with dry weather, while in other places it is associated with rainy weather. The wet season is the period of vegetation growth within the savanna climate regime. Where the wet season is associated with a shift in the prevailing winds. In the northern Atlantic Ocean, a tropical cyclone season occurs from 1 June to 30 November. The statistical peak of the Atlantic hurricane season is 10 September, the Northeast Pacific Ocean has a broader period of activity, but in a similar time frame to the Atlantic. The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March, in the North Indian basin, storms are most common from April to December, with peaks in May and November
Summer
–
A field during summer in
Belgium
Summer
–
Wet season
thunderstorm at night in
Darwin, Australia.
Summer
–
Image of
Hurricane Lester from late August 1992.
Summer
24.
Winter
–
Winter is the coldest season of the year in polar and temperate climates, between autumn and spring. Winter is caused by the axis of the Earth in that hemisphere being oriented away from the Sun, different cultures define different dates as the start of winter, and some use a definition based on weather. When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere, in many regions, winter is associated with snow and freezing temperatures. The moment of winter solstice is when the elevation with respect to the North or South Pole is at its most negative value, meaning this day will have the shortest day. The English word winter comes from the Proto-Indo-European root wend, relating to water, the tilt of the Earths axis relative to its orbital plane plays a large role in the formation of weather. The Earth is tilted at an angle of 23. 44° to the plane of its orbit, when it is winter in the Northern Hemisphere, the Southern Hemisphere faces the Sun more directly and thus experiences warmer temperatures than the Northern Hemisphere. Conversely, winter in the Southern Hemisphere occurs when the Northern Hemisphere is tilted more toward the Sun, from the perspective of an observer on the Earth, the winter Sun has a lower maximum altitude in the sky than the summer Sun. During winter in either hemisphere, the altitude of the Sun causes the sunlight to hit that hemisphere at an oblique angle. In regions experiencing winter, the amount of solar radiation is spread out over a larger area. This effect is compounded by the distance that the light must travel through the atmosphere. Compared with these effects, the changes in the distance of the earth from the sun are negligible, the manifestation of the meteorological winter in the northerly snow–prone parallels is highly variable depending on elevation, position versus marine winds and the amount of precipitation. A case in point is Canada, a country associated with tough winters. Winnipeg on the Great Plains at a distance from large bodies of water has a January high of −11.3 °C. In comparison, Vancouver on the coast with an influence from moderating Pacific winds has a January low of 1.4 °C with days well above freezing at 6.9 °C. Both areas are on the 49th parallel north and in the western half of the continent. Winter is often defined by meteorologists to be the three months with the lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere, the coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June, July or August in the Southern Hemisphere. Blizzards often develop and cause many transportation delays, diamond dust, also known as ice needles or ice crystals, forms at temperatures approaching −40 °F due to air with slightly higher moisture from aloft mixing with colder, surface based air
Winter
–
A
snow -covered park in front of the
Cathedral of Learning in
Pittsburgh,
Pennsylvania during winter
Winter
–
Conifer forest in the
Pillapalu,
Estonia, in January 2014
Winter
–
The Old Town of
Tallinn,
Estonia, full of snow on 1 January 2010
Winter
–
Tierra del Fuego,
Argentina
25.
Equinox
–
An equinox is the moment in which the plane of Earths equator passes through the center of the Sun, which occurs twice each year, around 20 March and 23 September. On an equinox, day and night are of equal duration all over the planet. They are not exactly equal, however, due to the size of the sun. To avoid this ambiguity, the word equilux is sometimes used to mean a day in which the durations of light, see Length of equinoctial day and night for further discussion. The word is derived from the Latin aequinoctium, aequus and nox, the equinoxes are the only times when the solar terminator is perpendicular to the equator. As a result, the northern and southern hemispheres are equally illuminated, the word comes from Latin equi or equal and nox meaning night. In other words, the equinoxes are the times when the subsolar point is on the equator. The subsolar point crosses the equator moving northward at the March equinox, the equinoxes, along with solstices, are directly related to the seasons of the year. In the southern hemisphere, the equinox occurs in September. When Julius Caesar established the Julian calendar in 45 BC, he set 25 March as the date of the spring equinox. Because the Julian year is longer than the tropical year. By 1500 AD, it had drifted backwards to 11 March and this drift induced Pope Gregory XIII to create a modern Gregorian calendar. However, the leap year intervals in his calendar were not smooth and this causes the equinox to oscillate by about 53 hours around its mean position. This in turn raised the possibility that it could fall on 22 March, the astronomers chose the appropriate number of days to omit so that the equinox would swing from 19 to 21 March but never fall on the 22nd. Vernal equinox and Autumnal equinox, these names are direct derivatives of Latin. The equivalent common language English terms spring equinox and autumn equinox are even more ambiguous, March equinox and September equinox, names referring to the months of the year they occur, with no ambiguity as to which hemisphere is the context. They are still not universal, however, as not all use a solar-based calendar where the equinoxes occur every year in the same month. Northward equinox and southward equinox, names referring to the apparent direction of motion of the Sun
Equinox
–
The Earth in its orbit around the Sun causes the Sun to appear on the celestial sphere moving over the
ecliptic (red), which is tilted on the
Equator (white)
Equinox
–
Contour plot of the hours of daylight as a function of latitude and day of the year, showing approximately 12 hours of daylight at all latitudes during the equinoxes
Equinox
–
Diagram of the Earth's
seasons as seen from the north. Far right: December solstice.
Equinox
–
Diagram of the Earth's seasons as seen from the south. Far left: June solstice.
26.
Climate
–
Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
Climate
–
Atmospheric sciences
Climate
–
The world’s cloudy and sunny spots. NASA Earth Observatory map using data collected between July 2002 and April 2015.
27.
Northern Hemisphere
–
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined as being in the celestial hemisphere relative to the invariable plane of the solar system as Earths North pole. Due to the Earths axial tilt, winter in the Northern Hemisphere lasts from the December solstice to the March Equinox, the dates vary each year due to the difference between the calendar year and the astronomical year. Its surface is 60. 7% water, compared with 80. 9% water in the case of the Southern Hemisphere, the Arctic is the region north of the Arctic Circle. Its climate is characterized by cold winters and cool summers, precipitation mostly comes in the form of snow. The Arctic experiences some days in summer when the Sun never sets, the duration of these phases varies from one day for locations right on the Arctic Circle to several months near the North Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer lies the Northern Temperate Zone, the changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather, tropical regions are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months. In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the coriolis effect, as a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. These are best seen in circulation patterns in the North Atlantic. For the same reason, flows of air down toward the surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere, conversely, air rising from the northern surface of the Earth tends to draw air toward it in a counterclockwise pattern. Hurricanes and tropical storms spin counter-clockwise in the Northern Hemisphere, the shadow of a sundial moves clockwise in the Northern Hemisphere. When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere, the North Pole faces away from the galactic center of the Milky Way. The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the total human population of 7.3 billion people
Northern Hemisphere
–
Northern Hemisphere highlighted in blue
28.
Arctic
–
The Arctic is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Alaska, Canada, Finland, Greenland, Iceland, Norway, Russia, land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost-containing tundra. Arctic seas contain seasonal sea ice in many places, the Arctic region is a unique area among Earths ecosystems. For example, the cultures in the region and the Arctic indigenous peoples have adapted to its cold, in recent years, Arctic sea ice decline has been caused by global warming. Life in the Arctic includes organisms living in the ice, zooplankton and phytoplankton, fish and marine mammals, birds, land animals, plants, Arctic land is bordered by the subarctic. The word Arctic comes from the Greek word ἀρκτικός, near the Bear, northern, there are a number of definitions of what area is contained within the Arctic. The area can be defined as north of the Arctic Circle, the southern limit of the midnight sun. The Arctics climate is characterized by cold winters and cool summers and its precipitation mostly comes in the form of snow and is low, with most of the area receiving less than 50 cm. High winds often stir up snow, creating the illusion of continuous snowfall, average winter temperatures can be as low as −40 °C, and the coldest recorded temperature is approximately −68 °C. Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures, the Arctic is affected by current global warming, leading to Arctic sea ice shrinkage, diminished ice in the Greenland ice sheet, and Arctic methane release as the permafrost thaws. Due to the migration of the planets isotherms, the Arctic region is currently shrinking. Perhaps the most spectacular result of Arctic shrinkage is sea ice loss, there is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2040 to some time well beyond 2100. About half of the models show near-complete to complete sea ice loss in September by the year 2100. Arctic life is characterized by adaptation to short growing seasons with long periods of sunlight, Arctic vegetation is composed of plants such as dwarf shrubs, graminoids, herbs, lichens and mosses, which all grow relatively close to the ground, forming tundra. As one moves northward, the amount of available for plant growth decreases considerably. Colder summer temperatures cause the size, abundance, productivity and variety of plants to decrease, trees cannot grow in the Arctic, but in its warmest parts, shrubs are common and can reach 2 m in height, sedges, mosses and lichens can form thick layers. In the coldest parts of the Arctic, much of the ground is bare, non-vascular plants such as lichens and mosses predominate, along with a few scattered grasses, herbivores on the tundra include the Arctic hare, lemming, muskox, and caribou. They are preyed on by the owl, Arctic fox, Grizzly bear
Arctic
–
Artificially coloured topographical map of the Arctic region
Arctic
–
Location of the Arctic
Arctic
–
MODIS image of the Arctic
Arctic
–
Muskox
29.
Aurora (astronomy)
–
An aurora, sometimes referred to as a polar lights or northern lights, is a natural light display in the sky, predominantly seen in the high latitude regions. The resulting ionization and excitation of atmospheric constituents emits light of varying colour, the form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere, proton auroras are usually observed at lower latitudes. A region that currently displays an aurora is called the auroral oval, early evidence for a geomagnetic connection comes from the statistics of auroral observations. Elias Loomis, and later Hermann Fritz and S. Tromholt in more detail, day-to-day positions of the auroral ovals are posted on the internet. In northern latitudes, the effect is known as the Aurora Borealis or the Northern Lights, the former term was coined by Galileo in 1619, from the Roman goddess of the dawn and the Greek name for the north wind. The Aurora Australis is visible from southern latitudes in Antarctica, Chile, Argentina, New Zealand. A geomagnetic storm causes the auroral ovals to expand, and bring the aurora to lower latitudes and it was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The aurora can be seen best at this time, which is called magnetic midnight, Auroras also occur poleward of the auroral zone as either diffuse patches or arcs, which can be sub-visual. Auroras are occasionally seen in latitudes below the zone, when a geomagnetic storm temporarily enlarges the auroral oval. Large geomagnetic storms are most common during the peak of the sunspot cycle or during the three years after the peak. An aurora may appear overhead as a corona of rays, radiating from a distant and apparent central location, an electron spirals about a field line at an angle that is determined by its velocity vectors, parallel and perpendicular, respectively, to the local geomagnetic field vector B. This angle is known as the “pitch angle” of the particle, the distance, or radius, of the electron from the field line at any time is known as its Larmor radius. The pitch angle increases as the travels to a region of greater field strength nearer to the atmosphere. Thus it is possible for particles to return, or mirror. Other particles that do not mirror enter the atmosphere and contribute to the display over a range of altitudes. Other types of auroras have been observed from space, e. g. poleward arcs stretching sunward across the cap, the related theta aurora. These are relatively infrequent and poorly understood, there are other interesting effects such as flickering aurora, black aurora and sub-visual red arcs
Aurora (astronomy)
–
Images of the aurora australis and aurora borealis from around the world, including those with rarer red and blue lights
Aurora (astronomy)
–
25-second exposure of the aurora australis from
Amundsen-Scott S.P.S.
Aurora (astronomy)
–
Northern lights over
Calgary
Aurora (astronomy)
–
Red and green auroras, Norway
30.
Lakes Entrance, Victoria
–
Lakes Entrance is a seaside resort and fishing port in eastern Victoria, Australia. It is situated approximately 320 kilometres east of Melbourne, near a managed, at the 2011 census, Lakes Entrance had a population of 4,569. The township was originally named Cunninghame, the Post Office of that opening on 5 February 1870. It was renamed Lakes Entrance on 1 January 1915, spectacular views of The Entrance and of the Lakes can be seen from various look-outs on Jemmys Point. The Princes Highway leaves the north-east side of the town through hilly countryside towards Nowa Nowa, Lakes Entrance is predominantly a fishing and tourism-driven town, the main beach front is a safe harbour for many major commercial fishing and recreational watersport operations. The surf beach is patrolled by the Lakes Entrance Surf Life Saving Club between November and March every summer, with patrols from late December to late January. The waterfront is populated by the fleet and two floating restaurants—Ferrymans Seafood Cafe and The Floating Dragon Dockside Restaurant. The main street consists of shops, caravan parks, a Safeway, a Target Country store that opened in 2007, the towns main residential areas lie farther inland. Lakes Entrance is a popular spot for camping in caravan parks. Nearby major towns include Bairnsdale and Orbost, Lakes Entrance falls within the Shire of East Gippsland. Minor towns include Swan Reach, Johnsonville, Kalimna, Nicholson, Metung, the town has an Australian rules football team competing in the East Gippsland Football League. The town is home to a club in the East Gippsland Hockey Association, although the club still plays under the name of its original home town. Golfers play at the course of the Lakes Entrance Golf Club on Golf Links Road, Lakes Entrance is the hometown of, Aaron Symons, Professional football coach with Dempo in the Indian I-League The Lakes National Park Official East Gippsland tourism website
Lakes Entrance, Victoria
–
Lakes Entrance. The town is on the left and "The Entrance" is near the centre
Lakes Entrance, Victoria
–
90 mile beach
Lakes Entrance, Victoria
–
The Entrance to Gippsland Lakes at Lakes Entrance
Media related to Southern Hemisphere at Wikimedia Commons
