Latitude is measured as the angle between a line from earth's center to the measurement point. Specifies north south position.
Longitude is measured as the angle between a line from earth's center to the prime meridian (green which); they are circular with identical radii at a given latitude. Keeping accurate time is necessary to measure longitude.
Lines of latitude are always the same distance apart, but distance between two lines of longitude varies with latitude.
Magellan expedition 16th century- First voyage around the world. Only 18 out of 260 sailors managed to return after three years of dangerous travel and circumnavigating the globe.
Continued Research in Oceans
United States Exploring Expedition launched in 1838 was a naval and scientific expedition.
HMS Beagle, on which Charles Darwin served as a naturalist, voyaged to South America and some pacific islands
Matthew Maury 1847 produced the first atlas on winds and currents based on ship logs
HMS Challenger expedition- first oceanic expedition dedicated to scientific research
20th century Satellite technology- more data, less expensive, global.
stats
Average Depth- 3,796 meters
Average temp- 3.9 degrees, 39 degrees F
Average Salinity- 34,482 grams per kg.
Average Land Elevation- 840 meters
Age- 4 billion years
Mean temp of the earth 14.0 C or 16 C
Chemical Comp of Earth
Lithosphere- Strong, rocky, outer shell of the solid Earth including all the crust and the upper part of the mantle to a depth of 100 km. forms the plates
Asthenosphere- weak, ductile layer of the mantle beneath the lithosphere; deforms to accommodate motions to the overlying plates.
Deep Mantle- Mantle beneath the asthenosphere
Outer Core- Liquid shell composed of mostly iron
Inner Core- Innermost sphere composed primarily of solid iron.
Crust: COLD, RIGID, THIN SURFACE
Continental Crust
Relatively light