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Vocabulary Definitions - Earth in Space

Period of rotation-time it takes a planet to make one rotation on its

Axis  (day)

 

Period of revolution- time it takes a planet to make one revolution

around the sun  (year)

Axis-Imaginary vertical line through the center of body around which

the body rotates, or spins

 

Summer solstice-time of year when the northern hemisphere has its

longest day and the southern hemisphere has its shortest day:

beginning of summer in the northern hemisphere. June 21st-22nd

 

Winter solstice-time of year when the northern hemisphere has its

shortest day and the southern hemisphere has its longest day:

beginning of winter in the northern hemisphere. December 22nd-23rd

 

Vernal equinox-time of year when day and night are of equal length:

beginning of Spring in the Northern Hemisphere. March 21st-22nd

 

Autumnal equinox-time of year when day and night are of equal

length: beginning of autumn in the Northern Hemisphere. September 21st-22nd