Earth Sciences 1086F/G Chapter Notes - Chapter 7: North American Plate, Mantle Plume, Cambrian
4 Jan 2021
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Document Summary
Third planet from sun (1. 0 astronomical unit, 150 million kilometres) Densest major body in the solar system (5. 5g/cm3) Plane of orbit (ecliptic) is only 7 degrees from sun"s equatorial plane. Orbital path is nearly circular (angle of obliquity/tilt angle tilt of rotational axis is responsible for seasons) When earth rotates, rotational axis moves makes a cone-like pattern called precession. North pole star thuban during egyptian pyramids being built. Strong magnetic field generated by electrical currents in iron-rich core. Interaction of liquid metal of outer core flowing past solid metal of inner core establishes an electrical current which in turn produces a magnetic field. Earth"s magnetic field is uniquely strong compared to terrestrial planet mercury has weak, venus has none, mars is extremely weak. Atmosphere is unique to earth contains 78% nitrogen, 21% oxygen, other 1% consists of many elements and compounds. Accretion growth by accumulation of smaller bodies, dust, and gas.
