question: How do you differentiate east from west at the poles?
comment: Exactly at the poles, there is no east or west. From the south pole, every direction is north. Close to the poles, east and west still exist; that latitude band is just a really small circle
passages: West
  
  West is one of the four cardinal directions or points of the compass. It is the opposite direction from east.
  
  Section::::Etymology.
  
  The word "west" is a Germanic word passed into some Romance languages ("ouest" in French, "oest" in Catalan, "ovest" in Italian, "oeste" in Spanish and Portuguese). It stems from the Indo-European root "*wes" reduced from "*wes-pero" 'evening, night' which is related to Old Greek "hesperos" and Latin "vesper" 'evening; west'.
  
  Section::::Navigation.
  
  To go west using a compass for navigation, one needs to set a bearing or azimuth of 270°.
   In some languages, points of the compass bear names etymologically derived from words for sunrise and sunset. The English words "orient" and "occident", meaning "east" and "west", respectively, are descended from Latin words meaning "sunrise" and "sunset". The word "levant", related e.g. to French ""(se) lever"" meaning "lift" or "rise" (and also to English "elevate"), is also used to describe the east. In Polish, the word for east "wschód" ("vskhud"), is derived from the morpheme "ws" – meaning "up", and "chód" – signifying "move" (from the verb "chodzić" – meaning "walk, move"), due to the act of the Sun coming up from behind the horizon. The Polish word for west, "zachód" ("zakhud"), is similar but with the word "za" at the start, meaning "behind", from the act of the Sun going behind the horizon. In Russian, the word for west, "запад" ("zapad"), is derived from the words "за" – meaning "behind", and "пад" – signifying "fall" (from the verb "падать" – "padat"'), due to the act of the Sun falling behind the horizon. In Hebrew, the word for east is 'מזרח', which derives from the word for rising, and the word for west is 'מערב', which derives from the word for setting.
   By convention, the right hand side of a map is east. This convention has developed from the use of a compass, which places north at the top. However, on maps of planets such as Venus which rotate retrograde, the left hand side is east.
  
  To go east using a compass for navigation, one sets a bearing or azimuth of 90°.
  
  Section::::Cultural.
   Reasonably accurate folk astronomy, such as is usually attributed to Stone Age peoples or later Celts, would arrive at east and west by noting the directions of rising and setting (preferably more than once each) and choosing as prime direction one of the two mutually opposite directions that lie halfway between those two. The true folk-astronomical definitions of east and west are "the directions, a right angle from the prime direction, that are closest to the rising and setting, respectively, of the sun (or moon).
  
  Section::::Cultural references.
   Latitude and longitude uniquely describe the location of any point on Earth. Latitude may be simply calculated from astronomical or solar observation, either at land or sea, interrupted only by cloudy skies. Longitude, on the other hand, requires both astronomical or solar observation and some form of time reference to a longitude reference point. John Harrison produced the first precise marine chronometer in 1761.
   Section::::Historical contrast between East and West.
   One method is to use the Prime Meridian as the dividing line between east and west. This meridian running through Greenwich, London, is defined as zero degrees longitude and could be called the "least eastern" and "least western" place in the world. The 180th meridian, on the opposite side of the globe, is therefore the "easternmost" and "westernmost" place in the world.
  
  Another method is to use the International Date Line as the easternmost–westernmost extreme. On the equinox, the easternmost place would be where the day first begins, and the westernmost is where the day last ends.
   BULLET::::- Magnetic bearing + deviation = Compass bearing
  
  These rules are often combined with the mnemonic "West is Best, East is least"; that is to say, add W declinations when going True headings to Magnetic Compass, and subtract E ones.
  
  Another simple way to remember which way to apply the correction for Continental USA is:
  
  BULLET::::- For locations east of the agonic line (zero declination), roughly east of the Mississippi: The magnetic bearing is always bigger.
  
  BULLET::::- For locations west of the agonic line (zero declination), roughly west of the Mississippi: The magnetic bearing is always smaller.
  
  Common abbreviations are:
   Section::::Historical concepts.
   East
  
  East is one of the four cardinal directions or points of the compass. It is the opposite direction from west.
  
  Section::::Etymology.
  
  The word "east" comes from Middle English "est", from Old English "ēast", which itself comes from the Proto-Germanic *"aus-to-" or *"austra-" "east, toward the sunrise", from Proto-Indo-European *aus- "to shine," or "dawn". This is similar to Old High German "*ōstar" "to the east", Latin "aurora" "dawn", and Greek "ēōs" . "Ēostre", a Germanic goddess of dawn, might have been a personification of both dawn and the cardinal points.
  
  Section::::Navigation.
   BULLET::::- Southernmost point — Cocos Island, Costa Rica
  
  BULLET::::- Westernmost point — The westernmost point depends on the definition of "westernmost". If following the International Date Line, it would be Cape Wrangell on Attu Island, Alaska, United States . However, if the border between east and west is defined by the 180th meridian, the westernmost point is the West Point of Amatignak Island , as Attu Island is in the Eastern Hemisphere.
   In the polar regions, directions can become complicated, with all geographic north–south lines converging at the poles. The difference between UPS grid north and true north can therefore be anything up to 180°—in some places, grid north is true south, and vice versa. UPS grid north is arbitrarily defined as being along the prime meridian in the Antarctic and the 180th meridian in the Arctic; thus, east and west on the grids when moving directly away from the pole are along the 90°E and 90°W meridians respectively.
  
  Section::::Projection system.
   West is the direction opposite that of the Earth's rotation on its axis, and is therefore the general direction towards which the Sun appears to constantly progress and eventually set.
  
  Moving continuously west is following a circle of latitude.
  
  Section::::Cultural.
  
  The phrase "the West" is often spoken in reference to the Western world, which includes the European Union (also the EFTA countries), the Americas, Israel, Australia, New Zealand and (in part) South Africa.
   Section::::Reception.
   BULLET::::- Northeast (NE), 45°, halfway between north and east, is the opposite of southwest.
  
  BULLET::::- Southeast (SE), 135°, halfway between south and east, is the opposite of northwest.
  
  BULLET::::- Southwest (SW), 225°, halfway between south and west, is the opposite of northeast.
  
  BULLET::::- Northwest (NW), 315°, halfway between north and west, is the opposite of southeast.
  
  Section::::Additional points.:Other.
   The almost perfect circle (the earth is an oblate spheroid that is fatter around the equator), drawn with a line, demarcating the Eastern and Western Hemispheres must be an arbitrarily decided and published convention, unlike the equator (an imaginary line encircling Earth, equidistant from its poles), which divides the Northern and Southern Hemispheres. The prime meridian at 0° longitude and the antimeridian, at 180° longitude, are the conventionally accepted boundaries, since they divide eastern longitudes from western longitudes. This convention was established in 1884 at the International Meridian Conference held in Washington, D.C. where the standard time concepts of Canadian railroad engineer Sir Sandford Fleming were adopted. The Hemispheres agreed do not correspond with exact continents. Portions of Western Europe, West Africa, Oceania, and extreme northeastern Russia are in the Western Hemisphere, divorcing it from the continents which form the touchstone for most geopolitical constructs of "the East" and "the West".
   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 At the South Pole, all directions face north. For this reason, directions at the Pole are given relative to "grid north", which points northward along the prime meridian. Along tight latitude circles, clockwise is east, and counterclockwise is west, opposite to the North Pole.
   Section::::Roles of east and west as inherently subsidiary directions.
  
  While the choice of north over south as prime direction reflects quite arbitrary historical factors, east and west are not nearly as natural alternatives as first glance might suggest. Their folk definitions are, respectively, "where the sun rises" and "where it sets". Except on the Equator, however, these definitions, taken together, would imply that
  
  BULLET::::- east and west would not be 180 degrees apart, but instead would differ from that by up to twice the degrees of latitude of the location in question, and
   Section::::Longitude in the United States.
  
  Latitude and longitude uniquely describe the location of any point on Earth. Latitude may be simply calculated from astronomical or solar observation, either at land or sea, interrupted only by cloudy skies. Longitude, on the other hand, requires both astronomical or solar observation and some form of time reference to a longitude reference point. John Harrison produced the first precise marine chronometer in 1761.
   However, "planetocentric longitude" is always measured positively to the east, regardless of which way the planet rotates. "East" is defined as the counter-clockwise direction around the planet, as seen from above its north pole, and the north pole is whichever pole more closely aligns with the Earth's north pole. Longitudes traditionally have been written using "E" or "W" instead of "+" or "−" to indicate this polarity. For example, the following all mean the same thing:
   Easting and northing coordinates are commonly measured in metres from the axes of some horizontal datum. However, other units (e.g., survey feet) are also used. The coordinates are most commonly associated with the Universal Transverse Mercator coordinate system (UTM), which has unique zones that cover the Earth to provide detailed referencing.
  
  Section::::Notation and conventions.
  
  Locations can be found using easting/northing (or " x", "y") pairs. The pair is usually represented conventionally with easting first, northing second.
   In the United States, the major media hub is the East Coast city of New York. CBS Sports has its headquarters within the Manhattan borough of the city, and NBC Sports, MLB Network and NHL Network all have their hubs in the metropolitan area (NBC is based in Stamford, Connecticut, while MLB/NHL share the former studios of MSNBC in Secaucus, New Jersey); ESPN is in Bristol, Connecticut, which is roughly equidistant to both New York and Boston. Meanwhile, Turner Sports is based in Atlanta, Georgia, also on the East Coast. Canada's two major media hubs, Toronto (for English-language media) and Montréal (for French), are also both in the Eastern Time Zone. Buccigross wrote that an imbalance is understandable from Eastern writers, considering they are influenced by their close proximity and easier access to the happenings in the East. The East is home to nearly half of the country's population and is both more densely populated and was settled and developed much earlier than the West.
   For example, the peak of Mount Assiniboine (at ) in UTM Zone 11 is represented by codice_1. Other conventions can also be used, such as a truncated grid reference, which would shorten the example coordinates to codice_2.
  
  Negative northing and easting values indicate a position due south and west of the origin, respectively.
   Consequently, the meridians of 20°W and the diametrically opposed 160°E are often used outside of matters of physics and navigation, which includes all of the European and African mainlands, but also includes a small portion of northeast Greenland (typically reckoned as part of North America) and excludes more of eastern Russia and Oceania (e.g., New Zealand). Prior to the global adoption of standard time, numerous prime meridians were decreed by various countries where time was defined by local noon (thereby, local meridian).
   Magnetic variation (also known as magnetic declination) is different depending on the geographic position on the globe. The Magnetic North Pole is currently in Northern Canada and is moving generally south. A straight line can be drawn from the Geographic North Pole, down to the Magnetic North Pole and then continued straight down to the equator. This line is known as the agonic line, and the line is also moving. In the year 1900, the agonic line passed roughly through Detroit and then was east of Florida. It currently passes roughly west of Chicago, IL, and through New Orleans, LA. If a navigator is located on the agonic line, then variation is zero: the Magnetic North Pole and the Geographic North Pole appear to be directly in line with each other. If a navigator is east of the agonic line, then the variation is westward; magnetic north appears slightly west of the Geographic North Pole. If a navigator is west of the agonic line, then the variation is eastward; the Magnetic North Pole appears to the east of the Geographic North Pole. The farther the navigator is from the agonic line, the greater the variation. The local magnetic variation is indicated on NOAA nautical charts at the center of the compass rose. The magnetic variation is indicated along with the year of that variation. The annual increase or decrease of the variation is also usually indicated, so that the variation for the current year can be calculated.
  
presuppositions: There is east and west at the poles.
corrections: Exactly at the poles, there is no east or west.
raw_presuppositions: There is east and west at the poles. There is east and west at the poles.
raw_corrections: Exactly at the poles, there is no east or west. Exactly at the poles, there is no east or west.