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A Geographic Coordinate System (GCS) employs latitude and longitude to precisely define locations on the Earth's curved surface.
Answer: True
A Geographic Coordinate System (GCS) is fundamentally defined by its use of latitude and longitude to specify locations directly on the Earth's spherical or geodetic surface, serving as a foundational spatial reference system.
Geographic coordinate systems measure positions using linear distances, similar to Cartesian coordinate systems.
Answer: False
Geographic coordinate systems utilize angular measurements (latitude and longitude) to define positions on a curved surface, fundamentally differing from Cartesian systems which employ linear distances in a flat plane.
A complete GCS specification requires only latitude and longitude values to be unambiguous.
Answer: False
A complete Geographic Coordinate System (GCS) specification necessitates the inclusion of a geodetic datum, which defines the reference ellipsoid and its orientation, beyond just latitude and longitude values to ensure unambiguous location definition.
Latitude is defined as the angle between the equatorial plane and a line connecting a surface point to the Earth's center (geocentric latitude).
Answer: True
Latitude, specifically geocentric latitude, is defined as the angle formed by the equatorial plane and a line connecting a point on the Earth's surface to the Earth's center.
Parallels are lines of longitude that converge at the poles.
Answer: False
Parallels are circles on the Earth's surface that join points of the same latitude and run east-west; lines of longitude, known as meridians, are what converge at the poles.
Longitude measures the angle east or west between a reference meridian and another meridian passing through a specific point.
Answer: True
Longitude is defined as the angular distance, measured eastward or westward, from the prime meridian to any given meridian passing through a specific location.
What is the fundamental characteristic of a Geographic Coordinate System (GCS)?
Answer: It defines locations using angles of latitude and longitude on a spherical Earth.
The fundamental characteristic of a Geographic Coordinate System (GCS) is its utilization of angular measurements, specifically latitude and longitude, to define positions on a spherical or geodetic model of the Earth, distinguishing it from linear, Cartesian systems.
Which component is essential for a complete GCS specification beyond latitude and longitude?
Answer: A geodetic datum defining the reference ellipsoid and its orientation.
A complete Geographic Coordinate System (GCS) specification requires the inclusion of a geodetic datum, which defines the reference ellipsoid and its orientation, to ensure unambiguous location definition beyond latitude and longitude alone.
Which of the following correctly defines latitude?
Answer: The angle formed by the plane of the equator and a line connecting a surface point to the Earth's center.
Latitude is defined as the angle formed by the equatorial plane and a line connecting a point on the Earth's surface to the Earth's center (or the normal to the ellipsoid, depending on the type of latitude).
What are parallels in the context of geographic coordinates?
Answer: Circles on the Earth's surface joining points of the same latitude, running east-west.
Parallels are defined as circles on the Earth's surface that connect all points of equal latitude, running parallel to the Equator in an east-west direction.
What is 'Null Island' humorously referred to as in the context of a graticule?
Answer: The intersection of the Prime Meridian and the Equator (0° latitude, 0° longitude).
'Null Island' is the facetious designation for the point where the Prime Meridian (0° longitude) and the Equator (0° latitude) intersect, located in the Gulf of Guinea.
Eratosthenes of Cyrene is credited with developing the foundational geographic coordinate system in the 3rd century BC.
Answer: True
The development of the foundational geographic coordinate system is widely attributed to Eratosthenes of Cyrene, who established such a system in his work during the 3rd century BC.
Hipparchus improved the GCS by using stellar measurements for latitude but continued to rely on solar altitude for longitude.
Answer: False
Hipparchus advanced the Geographic Coordinate System by utilizing stellar measurements for latitude and employing the timing of lunar eclipses for longitude determination, rather than relying on solar altitude for longitude.
Marinus of Tyre created a world map using coordinates measured west from a prime meridian, a system later refined by Ptolemy.
Answer: False
Marinus of Tyre developed a system using coordinates measured east from a prime meridian, which was subsequently adopted and refined by Ptolemy.
Marinus and Ptolemy accurately calculated the circumference of the Mediterranean Sea, leading to precise mapping.
Answer: False
While Marinus and Ptolemy made significant contributions, their calculations of the Mediterranean Sea's circumference were inaccurate, specifically underestimating its size, which impacted mapping precision.
Who is generally credited with the invention of the geographic coordinate system, and in which century?
Answer: Eratosthenes of Cyrene, in the 3rd century BC
Eratosthenes of Cyrene is generally credited with developing the foundational geographic coordinate system during the 3rd century BC.
What significant improvement did Hipparchus introduce to the geographic coordinate system?
Answer: He used stellar measurements for latitude and timed lunar eclipses for longitude.
Hipparchus significantly improved the geographic coordinate system by employing stellar measurements for latitude determination and utilizing the timing of lunar eclipses for more accurate longitude calculation.
How did Marinus of Tyre and Ptolemy contribute to coordinate measurements?
Answer: Marinus compiled a gazetteer and used coordinates measured east from a prime meridian; Ptolemy adopted and refined this.
Marinus of Tyre created a world map using coordinates measured east from a prime meridian, and Ptolemy later adopted and refined this system in his influential work.
What was the primary error in the calculations of Marinus and Ptolemy regarding the Mediterranean Sea?
Answer: They underestimated its circumference.
The principal error in the calculations by Marinus and Ptolemy concerning the Mediterranean Sea was an underestimation of its actual circumference.
The 1884 International Meridian Conference established the prime meridian passing through Paris.
Answer: False
The 1884 International Meridian Conference designated the prime meridian passing through the Royal Observatory in Greenwich, England, as the international standard, not Paris.
The international prime meridian is located at the 0° latitude line.
Answer: False
The international prime meridian is defined by 0° longitude, not 0° latitude, which is the Equator.
A geodetic datum is unnecessary for precisely measuring actual locations on the physical Earth.
Answer: False
A geodetic datum is critically important for precisely measuring actual locations on the physical Earth, as it establishes the relationship between a mathematical model of the Earth and its actual surface.
Horizontal datums are used for measuring elevation, while vertical datums are used for latitude and longitude.
Answer: False
Horizontal datums are used for measuring latitude and longitude, while vertical datums are employed for measuring elevation or altitude.
Using different geodetic datums for the same location will always result in identical latitude and longitude values.
Answer: False
Employing different geodetic datums for the same physical location will yield different latitude and longitude values due to variations in the reference ellipsoid and its orientation.
Specifying the datum is unimportant when using spatial reference systems, as coordinate interpretation is universal.
Answer: False
Specifying the datum is crucial for accurate coordinate interpretation in spatial reference systems, as different datums can lead to significant positional discrepancies.
WGS 84 and ITRF are examples of regional datums designed for specific countries.
Answer: False
WGS 84 and ITRF are examples of global datums, designed for worldwide application, in contrast to regional datums which are specific to particular geographic areas or countries.
Regional datums, like ED50, are often defined by national cartographical organizations.
Answer: True
Regional datums, such as the European Datum 1950 (ED50), are typically established and maintained by national cartographical organizations to best fit a specific geographic region.
In Greenwich, the WGS 84 datum and the OSGB36 datum differ by approximately 10 meters.
Answer: False
In Greenwich, the WGS 84 datum and the OSGB36 datum differ by approximately 112 meters, not 10 meters.
The World Geodetic System 1984 (WGS 84) is the default datum for most GPS equipment.
Answer: True
The World Geodetic System 1984 (WGS 84) serves as the standard, default datum for the vast majority of Global Positioning System (GPS) devices.
What was the outcome of the 1884 International Meridian Conference concerning the prime meridian?
Answer: It adopted the longitude of the Royal Observatory in Greenwich, England, as the international prime meridian.
The 1884 International Meridian Conference concluded with the adoption of the longitude of the Royal Observatory in Greenwich, England, as the international prime meridian.
What is the significance of the prime meridian in defining longitude?
Answer: It serves as the zero-degree reference line for measuring longitude east or west.
The prime meridian serves as the fundamental zero-degree reference line from which all longitude measurements, both east and west, are calculated.
Where is the international prime meridian located?
Answer: Through the Royal Observatory in Greenwich, England.
The international prime meridian is geographically located passing through the Royal Observatory in Greenwich, England.
What is the primary role of a geodetic datum in a GCS?
Answer: To bind a mathematical model of the Earth's shape to the physical Earth for accurate measurements.
The primary role of a geodetic datum is to establish a precise relationship between a mathematical model of the Earth's shape (e.g., an ellipsoid) and the physical Earth, thereby enabling accurate coordinate measurements.
Which type of datum is used for measuring elevation or altitude?
Answer: Vertical Datum
A vertical datum is specifically employed for the measurement of elevation or altitude, typically referencing a geoid model.
Why is it critical to specify the datum when using coordinates?
Answer: Different datums can result in positional errors of hundreds of meters for the same location.
Specifying the datum is critical because different datums can lead to significant positional discrepancies, potentially amounting to hundreds of meters, for the same physical location.
Which of the following is an example of a global datum?
Answer: World Geodetic System 1984 (WGS 84)
The World Geodetic System 1984 (WGS 84) is a prominent example of a global datum, designed for worldwide application and commonly used in GPS.
Regional datums, such as ED50, are typically characterized by:
Answer: Fitting an ellipsoid best to a specific portion of the Earth.
Regional datums, like ED50, are characterized by fitting a reference ellipsoid to a particular geographic area, optimizing accuracy within that region.
How much does the WGS 84 datum differ from the OSGB36 datum in Greenwich, according to the source?
Answer: Approximately 112 meters
The WGS 84 datum and the OSGB36 datum exhibit a difference of approximately 112 meters in Greenwich.
Which natural Earth movement can affect the accuracy of geographic coordinates over time?
Answer: Continental plate motion.
Continental plate motion is a significant natural Earth movement that can alter the positions of geographic coordinates over extended periods, necessitating dynamic datum adjustments.
What datum is commonly used as the default in most Global Positioning System (GPS) equipment?
Answer: World Geodetic System 1984 (WGS 84)
The World Geodetic System 1984 (WGS 84) is the standard datum utilized by most Global Positioning System (GPS) equipment.
One degree of latitude is approximately 110.6 kilometers long at the Equator on the WGS 84 spheroid.
Answer: True
On the WGS 84 spheroid at the Equator, one degree of latitude measures approximately 110.6 kilometers.
The length of one degree of longitude increases as latitude increases, converging towards the poles.
Answer: False
The length of one degree of longitude decreases as latitude increases, converging towards the poles, unlike the length of a degree of latitude which remains relatively constant.
The formula for calculating the length of a degree of longitude on the WGS 84 spheroid involves cosine functions of latitude.
Answer: True
The calculation for the length of a degree of longitude on the WGS 84 spheroid incorporates cosine functions of latitude, reflecting its variation with geographic position.
What is the approximate length of one degree of latitude at the Equator on the WGS 84 spheroid?
Answer: Approximately 110.6 kilometers
On the WGS 84 spheroid at the Equator, one degree of latitude measures approximately 110.6 kilometers.
How does the length of a degree of longitude change as latitude increases?
Answer: It decreases, converging towards the poles.
The length of one degree of longitude diminishes as latitude increases, converging towards zero at the poles due to the geometry of the Earth's meridians.
At the Equator, what is the approximate length of one degree of longitude?
Answer: 111.3 km
At the Equator, one degree of longitude measures approximately 111.3 kilometers.
Alternative encoding schemes for geographic coordinates were developed primarily because latitude-longitude pairs are easy to remember and communicate.
Answer: False
Alternative encoding schemes for geographic coordinates were developed because latitude-longitude pairs can be cumbersome to remember and communicate, not because they are inherently easy.
Geohash is an alternative encoding scheme for geographic coordinates based on the Morton Z-order curve.
Answer: True
Geohash is indeed an alternative encoding scheme for geographic coordinates that utilizes the principles of the Morton Z-order curve for its structure.
Wikimedia Commons is a source for finding media related to the geographic coordinate system.
Answer: True
Wikimedia Commons is a repository where one can find various media files, including those relevant to the study and illustration of the geographic coordinate system.
The navbox image shows primary meridians of longitude every 30 degrees east and west.
Answer: False
The navbox image displays primary meridians of longitude at intervals of 10 degrees east and west, with specific emphasis on the Prime Meridian (0°) and the 180° meridian, not every 30 degrees.
Authority control databases are referenced to help standardize information about geographic coordinate systems.
Answer: True
Authority control databases, such as GND or LoC, are utilized to standardize and manage information related to geographic coordinate systems, ensuring consistency and reliability.
Why were alternative encoding schemes for geographic coordinates developed?
Answer: To make coordinates easier to remember and communicate.
Alternative encoding schemes for geographic coordinates were developed to address the challenges associated with remembering and communicating standard latitude-longitude pairs.
Which of the following is mentioned as an alternative encoding scheme for geographic coordinates?
Answer: Maidenhead Locator System
The Maidenhead Locator System is cited as an example of an alternative encoding scheme for geographic coordinates, commonly used in amateur radio.
What is the purpose of referencing authority control databases like GND or LoC in the context of geographic information?
Answer: To standardize information and ensure consistency.
Authority control databases serve to standardize information and ensure consistency when referencing geographic coordinate systems and related entities.