Sextant 
 Sextant is a measuring instrument used to measure the angle of elevation of a celestial object above the horizon 
academickids.com/encyclopedia/index.php/Sex... Longitude 
 Longitude describes the location of a place on Earth east or west of a north-south line called the Prime Meridian 
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 The equator is an imaginary line drawn around a planet, halfway between the poles. The equator divides the surface into the Northern Hemisphere and the Southern Hemisphere... 
academickids.com/encyclopedia/index.php/Equ... Latitude 
 Latitude gives the location of a place on Earth north or south of the Equator.. 
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