Archive for the ‘Positioning and Geology’ Category

What is the highest point on Earth as measured from Earth’s center?

This item was filled under Facts, Places, Positioning and Geology, Technology


Mount Everest, located in Nepal and Tibet, is usually said to be the highest mountain on Earth. Reaching 29,029 feet at its summit, Everest is indeed the highest point above global mean sea level—the average level for the ocean surface from which elevations are measured. But the summit of Mt. Everest is not the farthest point from Earth’s center.

Earth is not a perfect sphere, but is a bit thicker at the Equator due to the centrifugal force created by the planet’s constant rotation. Because of this, the highest point above Earth’s center is the peak of Ecuador’s Mount Chimborazo, located just one degree south of the Equator where Earth’s bulge is greatest. The summit of Chimborazo is 20,564 feet above sea level. However, due to the Earth’s bulge, the summit of Chimborazo is over 6,560 feet farther from the center of the Earth than Everest’s peak. That makes Chimborazo the closest point on Earth to the stars.

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What is GPS?



For thousands of years, humans found their way by looking to the sky. Sailors used the constellations, sun, and moon to navigate to distant shores. Today, all that's needed is a device called a GPS receiver. GPS stands for Global Positioning System, and it lets us know where we are and where we are going anywhere on Earth.

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What is GRAV-D?

This item was filled under Facts, Ocean Science, Positioning and Geology

GRAV-D measures and monitors Earth’s gravity field to support the geoid—a model of roughly global mean sea level used to measure precise surface elevations—so that it may serve as the “zero reference surface” for all heights in the nation. Accurate heights are critical to many scientific endeavors, but are particularly important for protecting low-lying coastal ecosystems.

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What is subsidence?

This item was filled under Facts, Positioning and Geology

Land subsidence is a gradual settling or sudden sinking of the Earth’s surface. This geodetic mark in Louisiana is anchored deep below the ground and was level with the ground when it was originally placed there, but now the ground around the mark has subsided.

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What is glacial isostatic adjustment?

This item was filled under Facts, Ocean Science, Positioning and Geology
Glacial isostatic adjustment is the ongoing movement of land once burdened by ice-age glaciers.

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What is geocaching?

This item was filled under Facts, Positioning and Geology
Geocaching is an outdoor treasure-hunting activity that uses GPS-enabled devices.


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What is a geographic information system?

GIS is a computer system that captures, stores, checks, and displays information related to positions on Earth’s surface.

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What is tectonic shift?

This item was filled under Facts, Ocean Science, Positioning and Geology
Tectonic shift is the movement of the plates that make up Earth’s crust.

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What do geodesists do?

This item was filled under Basics, Facts, Positioning and Geology
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.

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What is the International Date Line?

The International Date Line serves as the "line of demarcation" between two consecutive calendar dates.

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