The Earth

Calculating the circumference of the Earth by Eratosthenes

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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

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

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Eclipses

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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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