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Nats notes - Science Scientific Explanations are tentative...

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Science: Scientific Explanations are tentative, not fully worked out or developed. They are empirical observations, based on observation or experience. Predictable and testable, they help provide a natural cause to explain the event. Science is a process of discovery that increases our body of knowledge. Information that can be learned. Science is not a list of facts to be memorized. Stars: Hydrogen (and helium) soon formed after the big bang. Other more complex compounds formed during the life cycles of stars. Stars use hydrogen as fuel, very high temperatures and pressures in the interiors of stars fuse hydrogen atoms together, nuclear fusion to create helium. Stars burn up when hydrogen is used up. Some die violently (supernovas) or some die quietly like our sun. Stars vary in size; giant stars burn out faster (10-20million years) and die violently. Supernovas create all the heaviest elements. We are truly made out of stardust . Intermediate size stars like the sun will die 10 billion years and end as cold balls of carbon. Stars are formed they are surrounded by rotating disks of carbon debris. Gravity pulls debris together to create planets that revolve in a constant motion. Heavier rocky planets close to the star and lighter gas rich stars farther from the star. The big bang is the universe not the solar system! Planets: 4 terrestrial: mercury, Venus, earth and mars 4 Jovian: Jupiter, Saturn, Uranus and Neptune. Wegners continental drift hypothesis: Pangaea Matching features: plant and animal fossils found on separate continents from linked patterns. Freshwater species cant cross-continents because of the open ocean between countries. Continuous mountain belts when Pangaea is reassembled Similar unusual sequence of rocks. Fit of the continents. Paleoclimates: widespread glaciations could be best explained if certain continents were located close to the South Pole. Seafloor contributed to a new understanding of Earths processes: Seafloor topography, age of the seafloor, Heat floor, Volcanoes and earthquakes. Age of Seafloor varies systematically; rocks of the seafloor are young compared to the rocks on the continents. Polarity of seafloor alternates between normal (+) and reverse (-) on both sides of the oceanic ridge. Plates: Rigid lithosphere is divided (by plate boundaries) into mobile tectonic plates Most plates composed of both continental and oceanic lithosphere (e.g., Africa, South America) Interaction along the plate boundaries accounts for: formation of new lithosphere, earthquakes, volcanoes and gradual movement of continents and plates. Many of these processes involve the melting of rocks. Melting of rocks produces magma associated with the formation of lithosphere at oceanic ridges and the generation of volcanoes near trenches. 3 changes lead to partial melting:
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This note was uploaded on 04/02/2008 for the course NATS 101 taught by Professor Allister during the Spring '08 term at Arizona.

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Nats notes - Science Scientific Explanations are tentative...

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