Untitled Quiz

Study Notes

The solar system consists of a medium-size star (the Sun) and eight planets orbiting it.
Planets are of two types: inner planets (terrestrial planets) and outer planets (Jovian planets).

Density: Inner planets have densities of 3 g/cm³ or more; outer planets have densities of 1.6 g/cm³ or less.

The Earth is estimated to be 4.5 to 4.6 billion years old.
This is determined by radiometric dating, using an instrument called a mass spectrometer (Uranium, Thorium).
The oldest rocks on Earth are found in the Canadian Shield (NW Territories near Great Slave Lake), dated at 3.96 billion years old. Prior to this, the oldest rocks were from the Isukasia region of Greenland, dating to 3.8 billion years.

Earth consists of four spheres: atmosphere, hydrosphere, biosphere, and lithosphere.

Consists of 78% nitrogen and 21% oxygen.
Contains minor amounts of carbon dioxide, argon, and water vapor.
Divided into layers, including troposphere (weather), stratosphere (ozone layer), mesosphere, thermosphere, and exosphere (outer space).

Drilling: Wells are mostly in the upper 7 km of the crust; the deepest (Soviet, Russian) well in the Kola Peninsula reached 12 km but stopped in 1989. Costs were over $100 million. Bottom hole temperature was 190°C.
Volcanic activity: Materials brought up from below (Xenoliths = foreign rock from the mantle found in lava). Only useful to depths of about 200 km.
Samples of the solar system (meteorites): Study of composition.
Seismic waves: Study of waves generated by earthquakes and explosions. Seismic wave speed increases with depth (pressure, and density increase downward).

Earth has a layered structure defined by composition (crust, mantle, core) and physical properties (lithosphere, asthenosphere, mesosphere, outer core, inner core).

Continental crust: Thick (up to 75 km), lower density (2.7 g/cm³), strongly deformed, and very old (billions of years).
Oceanic crust: Thinner (about 8 km), higher density (3.0 g/cm³), comparatively undeformed, and much younger (< 200 million years).

Lithosphere: Crust + upper portion of the mantle (solid & rigid), thickness varies from 10 km under oceans to 300 km under continents.
Mantle: Middle layer, rich in minerals containing iron, magnesium, silicon, and oxygen. At over 1000°C, it is solid but can deform slowly in a plastic manner.
Core: Composed of iron and nickel; remains extremely hot even after billions of years of cooling. Divided into a solid inner core and a liquid outer core. Inner core is solid due to extreme pressure.