The Earth

Calculating the circumference of the Earth by Eratosthenes


The first person to measure the size of the Earth was Eratosthenes, an ancient Greek scientist about 2,000 years ago. From basic geometry and the shadow of a tower he calculated the circumference of the Earth to be about 46,000 km. This value is slightly larger than the value measured today of about 40,000 km.
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Foucault's pendulum


Foucault's pendulum is a device invented by the French scientist Leon Foucault to test the Earth's rotation.
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Eclipses


An eclipse is the phenomenon by which one object occults another or enters into its shadow. A solar eclipse is the phenomenon of the moon covering the sun. A lunar eclipse occurs when the moon enters the earth's shadow..
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Earth Science
 

Introduction to Deep Earth Science

 
Astronomy
 

Astrophysics: Cosmology

 
 

Introduction to Astrophysics

 

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