Table of Contents

## geodesy

## What is geodesy and why is it important?

Geodesy is

**the science that accurately measures and understands our planet’s geometric shape, its orientation in space, and its field of gravity**. All of these things have an important effect on our lives, but are always working the background where most of us don’t notice.## What is geodesy and its types?

There are three branches of geodesy:

**geometric, gravimetric, and satellite**.## Who was the father of geodesy?

**Eratosthenes (third century B.C.E.)**is usually considered the father of scientific geodesy because he used measurements along the longest available, nearly meridional arc from Alexandria to Syene (now Aswan), in combination with the corresponding celestial arc measured with the sun dial at summer solstice.

## What is geodesy in GIS?

Geodesy (pronounced /d?i???d?si/), also called geodetics, a branch of earth sciences, is

**the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space**.## What is geodesy in short answer?

Geodesy is

**the science of accurately measuring and understanding the Earth’s geometric shape, orientation in space, and gravity field**. … In the past, geodesists determined the coordinates of points by using Earth-based surveying tools to measure the distances between points.## Who was the first Indian to know about geodesy?

**Abu Rayhan Biruni**(9731048) used a new method to accurately compute Earth’s circumference, by which he arrived at a value that was close to modern values for Earth’s circumference.

## What is the difference between geodesy and surveying?

Plane surveying uses normal instruments like chain, measuring tape, theodolite etc.

**Geodetic surveying uses more precise instruments and modern technology like GPS**.## What do Geodesists do?

Geodesists

**measure and monitor the Earth to determine the exact coordinates of any point**. Geodesists measure and monitor the Earth’s size and shape, geodynamic phenomena (e.g., tides and polar motion), and gravity field to determine the exact coordinates of any point on Earth and how that point will move over time.## Who first attempted to find out the size of the Earth?

The Greek philosopher

**Aristotle**(384-322 B.C.) is credited as the first person to try and calculate the size of the Earth by determining its circumference (the length around the equator) He estimated this distance to be 400,000 stades (a stadia is a Greek measurement equaling about 600 feet).## Who measured the size of Earth?

The first person to determine the size of Earth was

**Eratosthenes of Cyrene**, who produced a surprisingly good measurement using a simple scheme that combined geometrical calculations with physical observations. Eratosthenes was born around 276 B.C., which is now Shahhat, Libya. He studied in Athens at the Lyceum.## How did they determine the size of the Earth?

In the third century BCE , Eratosthenes, a Greek librarian in Alexandria , Egypt , determined the earth’s circumference to be 40,250 to 45,900 kilometers (25,000 to 28,500 miles) by

**comparing the Sun’s relative position at two different locations on the earth’s surface**.## What is CRS map?

**A Coordinate reference system (CRS) defines, with the help of coordinates, how the two-dimensional, projected map is related to real locations on the earth**. There are two different types of coordinate reference systems: Geographic Coordinate Systems and Projected Coordinate Systems.

## What is the difference between geodesic and geodetic?

There is a substantial difference between the two: Geodesy is basically geographical surveying and measurement, often at a large scale and including longitude and latitude issues, while a Geodesic is about extending some properties of straight lines to curved and other spaces.

## Is WGS84 geocentric or geodetic?

WGS84 and Lambert 93

Well, WGS84 is a **world geodetic system**! So the data is not projected! It is a geodetic system with geocentric or geodetic coordinates based on the EGM96 geoid, the reference ellipsoid IAG GRS80, and the original meridian is the Greenwich meridian.

## What are the sciences involved in geodesy?

Precise geodetic infrastructure enables ground- and space-based observations that are critical to a wide array of scientific disciplines, including

**seismology, geodynamics, climate science, hydrology, oceanography, meteorology, and space weather**.## Who Mapped the world first?

**Greek academic Anaximander**is believed to have created the first world map in 6th century BC. Anaximander reportedly believed that Earth was shaped like a cylinder, and that humans lived on the flat, top portion.

## Who is the father of surveying?

**Rennell**has been called the Father of Oceanography. In 1830 he was one of the founders of the Royal Geographical Society in London.

…

James Rennell.

Major James Rennel | |
---|---|

Occupation | Surveyor, cartographer, historian |

Employer | East India Company |

Spouse(s) | Jane Thackeray ? ( m. 1772??1810)? |

Parent(s) | John Rennell (father) |

## How long is Earth’s circumference?

## What square km of survey is treated as plane?

Geodetic Surveying

S.No. | Plane Surveying |
---|---|

6 | Area up to 196 Sq. Km. is treated as a plane |

7 | It is less accurate and less correct. |

8 | Used in general civil engineering survey project work |

9 | It employs traditional instruments like measuring tape, a chain, theodolite, etc. |

## What is the purpose of plane surveying?

Plane surveying is a common method of

**calculating land composition and topography**that involves considering a set expanse of land as a flat plane. This kind of land surveying works best for small areas of land, in large part because the Earth is not actually flat.## How does geodesy relate to the profession of land surveying?

Nowadays,

**geodesists produce extremely precise positional data by analyzing radio waves emitted by distant stars**. Once a control network is established, however, surveyors produce positions using instruments that measure angles and distances between locations on the Earth’s surface.