Who invented the first geographic coordinate system?
The invention of a geographic coordinate system is generally credited to Eratosthenes of Cyrene, who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC.
What is the Earth's geographic grid?
Instead, we divide the Earth into what is known as the geographic grid. This is made up of a system of imaginary circles, called parallels and meridians, which are shown in Figure 1.4.
Why isn't the Earth divided into a rectangular grid?
Because the Earth's surface is curved, we cannot divide it into a rectangular grid anymore than we could smoothly wrap a globe in a sheet of graph paper. Instead, we divide the Earth into what is known as the geographic grid. This is made up of a system of imaginary circles, called parallels and meridians, which are shown in Figure 1.4.
Where is the origin/zero point of the earth's grid?
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 (390 mi) south of Tema, Ghana .
Who invented longitude and latitude lines?
Hipparchus, a Greek astronomer (190–120 BC), was the first to specify location using latitude and longitude as co-ordinates. He proposed a zero meridian passing through Rhodes.
When was lat and long invented?
Eratosthenes in the 3rd century BCE first proposed a system of latitude and longitude for a map of the world.
What is geographic coordinate system in GIS?
A geographic coordinate system (GCS) is a reference framework that defines the locations of features on a model of the earth. It's shaped like a globe—spherical. Its units are angular, usually degrees. A projected coordinate system (PCS) is flat.
How did sailors calculate longitude?
Determining longitude was very difficult for 18th century sailors. Sailors used the grid formed by latitude and longitude lines to determine their precise position at sea. minutes that Greenwich time differed from the local time observed on board, the ship had traveled one longitudinal degree.
What came first longitude or latitude?
Latitude is written before longitude. Latitude is written with a number, followed by either “north” or “south” depending on whether it is located north or south of the equator.
Who solved the longitude problem?
one John HarrisonSobel reveals in her opening chapter that the problem of longitude was eventually solved by one John Harrison, an unschooled woodworker who had the genius to invent a pendulum-free clock that required no oil and ''would carry the true time from the home port, like an eternal flame, to any remote corner of the world. ''
What is a geographic grid system?
The geographic grid refers to the internationally-recognized system of latitude and longitude used to location positions on Earth's surface. Accurate use of this coordinate system is fundamental to the science of geography, which relies so heavily on maps as a medium of communication and analysis.
Is Google maps a GIS form?
Google Maps is probably the most widely used of the GIS platforms. Although it is not necessarily the best tool for complex data visualization, it is extremely robust and easy to use on mobile devices, and is better for the demonstration of routes and journey times.
What are the 4 components of a geographic coordinate system?
A GCS includes an angular unit of measure, a prime meridian, and a datum (based on a spheroid). A point is referenced by its longitude and latitude values. Longitude and latitude are angles measured from the earth's center to a point on the earth's surface. The angles often are measured in degrees (or in grads).
Why is longitude harder than latitude?
Determining longitude is much harder, because the earth's rotation continually changes the longitudinal position of a point on the earth's surface with respect to all celestial objects.
How did sailors know when it was noon?
Watching the Sun Sailors used the position of the sun as it moved from east to west to guide their route. At noon, they could determine north and south by the shadows the sun cast.
How did John Harrison solve the longitude problem?
In order to solve the problem of Longitude, Harrison aimed to devise a portable clock which kept time to within three seconds a day. This would make it far more accurate than even the best watches of the time.
When was the longitude problem solved?
They were finally awarded £8750 by Act of Parliament in June, 1773. Perhaps more importantly, John Harrison was finally recognized as having solved the longitude problem. In the meantime, Captain Cook had set out on his second voyage of discovery with K1, Kendall 's copy of H4.
How was latitude first measured?
The Phoenicians in 600 B.C. used the heavens to calculate latitude — as did the Polynesians in A.D. 400. Through the centuries, devices such as the gnomon and Arabian kamal were designed to measure the height of the sun and stars, and thereby determine the latitude.
When was the prime meridian established?
Finally, at an international convention called by U.S. President Chester Arthur in 1884, representatives from 25 countries agreed to pick a single, standard meridian. They chose the meridian passing through the Royal Observatory in Greenwich, England.
How did John Harrison solve the longitude problem?
In order to solve the problem of Longitude, Harrison aimed to devise a portable clock which kept time to within three seconds a day. This would make it far more accurate than even the best watches of the time.
What is a geographic grid Class 6?
Earth's grid: The network of parallels or latitudes and meridians or longitudes that divide the Earth's surface into a grid-like pattern is called...
What is the grid of the earth?
In order to locate correctly each and every place on the surface of the Earth, a network of horizontal and vertical lines is drawn on the globe. Th...
What is a grid answer?
A grid is a network of intersecting parallel lines, whether real or imaginary. Most American streets are laid out in a grid pattern, meaning the st...
What is a grid in geography class 9?
Answer: The network of the latitudes and the longitudes is known as a geographical grid.
What is a grid Why is it used?
In graphic design and word processing applications, a grid is a series of vertical and horizontal lines that are used to subdivide a page verticall...
Where did GIS come from?
GIS was an innovation that emerged from the Laboratory for Computer Graphics at the Harvard Graduate School of Design (GSD). The “Lab” was founded by Harvard College and GSD graduate Howard Fisher in 1965 with a grant from the Ford Foundation.
What is the impact of geographic information systems?
The intellectual implications of geographic information systems (GIS) are enormous, and their practical applications are now in worldwide use. Since its origins in the 1960s, GIS has enabled designers, planners, developers, public agencies, and communities to make better decisions about the shape of urbanization and its impact.
Why is ESRI important?
ESRI remains among the most important venues for the development of tools and techniques for the geographic analysis of design and planning decisions.
Where is the origin/zero point of the grid?
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 (390 mi) south of Tema, Ghana .
Who invented the coordinate system?
The invention of a geographic coordinate system is generally credited to Eratosthenes of Cyrene, who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC.
What is the name of the ellipsoid that best fits the area to be mapped?
In order to be unambiguous about the direction of "vertical" and the "horizontal" surface above which they are measuring, map-makers choose a reference ellipsoid with a given origin and orientation that best fits their need for the area to be mapped. They then choose the most appropriate mapping of the spherical coordinate system onto that ellipsoid, called a terrestrial reference system or geodetic datum .
How many meters is the WGS 84?
WGS 84 differs at Greenwich from the one used on published maps OSGB36 by approximately 112 m. The military system ED50, used by NATO, differs from about 120 m to 180 m. The latitude and longitude on a map made against a local datum may not be the same as one obtained from a GPS receiver.
What are some examples of global datums?
Examples of global datums include World Geodetic System (WGS 84, also known as EPSG:4326 ), the default datum used for the Global Positioning System, and the International Terrestrial Reference System and Frame (ITRF), used for estimating continental drift and crustal deformation. The distance to Earth's center can be used both for very deep positions and for positions in space.
What is the purpose of the stereographic coordinate system?
The stereographic coordinate system was superseded by the latitude-longitude system. Although no longer used in navigation, the stereographic coordinate system is still used in modern times to describe crystallographic orientations in the fields of crystallography, mineralogy and materials science.
What is the coordinate of every point that is expressed in ellipsoidal coordinates?
Every point that is expressed in ellipsoidal coordinates can be expressed as an rectilinear x y z ( Cartesian) coordinate. Cartesian coordinates simplify many mathematical calculations. The Cartesian systems of different datums are not equivalent.
What was the first method of determining longitude?
Eratosthenes in the 3rd century BCE first proposed a system of latitude and longitude for a map of the world. His prime meridian (line of longitude) passed through Alexandria and Rhodes, while his parallels (lines of latitude) were not regularly spaced, but passed through known locations, often at the expense of being straight lines. By the 2nd century BCE Hipparchus was using a systematic coordinate system, based on dividing the circle into 360°, to uniquely specify places on Earth. : 31 So longitudes could be expressed as degrees east or west of the primary meridian, as we do today (though the primary meridian is different). He also proposed a method of determining longitude by comparing the local time of a lunar eclipse at two different places, to obtain the difference in longitude between them. : 11 This method was not very accurate, given the limitations of the available clocks, and it was seldom done – possibly only once, using the Arbela eclipse of 330 BCE. But the method is sound, and this is the first recognition that longitude can be determined by accurate knowledge of time.
Who was the first person to use a clock to determine longitude?
Chronometers. The first to suggest travelling with a clock to determine longitude, in 1530, was Gemma Frisius , a physician, mathematician, cartographer, philosopher, and instrument maker from the Netherlands.
How accurate is the longitude of the island of Hven?
Jean Picard on Hven and Cassini in Paris made observations during 1671 and 1672, and obtained a value of 42 minutes 10 seconds (time ) east of Paris, corresponding to 10° 32' 30", about 12 minute of arc (1/5°) higher than the modern value.
How does the development of the telescope affect the longitude of a planet?
The development of the telescope and accurate clocks increased the range of methods that could be used to determine longitude. With one exception (magnetic declination) they all depend on a common principle, which was to determine an absolute time from an event or measurement and to compare the corresponding local time at two different locations. (Absolute here refers to a time that is the same for an observer anywhere on earth.) Each hour of difference of local time corresponds to a 15 degrees change of longitude (360 degrees divided by 24 hours).
What was the radius of John Flamsteed's telescope?
John Flamsteed 's mural arc. The telescope was mounted on a frame with a radius of about 2 metres. It was attached to a wall aligned to the meridian. There was rackwork and a micrometer, which are not shown
Where were the first astronomical observatories built?
The second half of the 17th century saw the foundation of two observatories, one in Paris and the other in London. The Paris Observatory was the first, being founded as an offshoot of the French Académie des Sciences in 1667. The Observatory building, to the south of Paris, was completed in 1672. Early astronomers included Jean Picard, Christiaan Huygens, and Dominique Cassini. : 165–177 The Observatory was not set up for any specific project, but soon became involved in the survey of France that led (after many delays due to wars and unsympathetic ministries) to the Academy's first map of France in 1744. The survey used a combination of triangulation and astronomical observations, with the satellites of Jupiter used to determine longitude. By 1684, sufficient data had been obtained to show that previous maps of France had a major longitude error, showing the Atlantic coast too far to the west. In fact France was found to be substantially smaller than previously thought.
When did longitude increase?
On land, the period from the development of telescopes and pendulum clocks until the mid-18th century saw a steady increase in the number of places whose longitude had been determined with reasonable accuracy, often with errors of less than a degree, and nearly always within 2–3°. By the 1720s errors were consistently less than 1°.
