vallis

A sinuous valley.

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vastitas

Widespread lowlands.

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Van Allen, James A.

American physicist. Van Allen discovered the Earth's radiation belts, which now bear his name, with an instrument aboard the first successful American satellite, Explorer 1.

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vent

The opening in the crust through which volcanic material erupts.

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Verne, Jules 1828-1905

French writer. Verne is considered to be the founder of modern science fiction. His novels include "Journey to the Center of the Earth" and "From the Earth to the Moon".

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volatile

Compounds with low melting temperatures, such as hydrogen, helium, water, ammonia, carbon dioxide and methane.

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volcano

(1) A vent in the planetary surface through which magma and associated gases and ash erupt. (2) The form or structure produced by the erupted materials.