Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
EARTH’S SHAPE, DIMENSIONS, AND INTERNAL HEAT Earth Science 11 Corpuz Earth’s Motion • Rotation Rotates around its axis Period = 24 hours = 1 day Axis tilted at 23.5ᵒ • Revolution Revolves around the sun Period = 365.25 days = 1 year • Precession A “wobble” in Earth’s motion The conical motion of Earth’s axis Period = 26 000 years Earth’s Shape • Evidence for Spherical Earth Can go all the way around without falling off The top of a ship’s mast is the first thing you see as it approaches your location (discovered by Magellan, 1522) Earth casts a curved shadow on the moon during a lunar eclipse Position of constellations change as you move north or south • Earth is an Oblate Spheroid = “flattened sphere” Due to rotation Diameter at equator is 42 km greater than diameter at poles Circumference around equator is 67 cm greater than circumference around poles Earth’s Density • Earth’s Specific Gravity (Relative Density) Density as compared to water - water = 1.0 g/mL - Earth’s crust = 3.0 g/mL - Earth’s core = 8.0 g/mL - Average = 5.5 g/mL (Earth’s specific gravity) Earth’s Heat • Earth’s Internal Heat Surface temperatures do not penetrate below 20 m Past 20 m, temperature in the crust increases at about 1ᵒC for every 40 m depth (=geothermal gradient) Sources of heat: - Radioactive isotopes - Leftover heat from Earth’s formation, trapped in by crustal rocks - Friction between tectonic plates - Tidal stress from moon’s gravity Earth’s Energy (Heat) Sources • The Earth has 2 sources of energy: 1. Sun The fusion (putting together) of hydrogen atoms into helium atoms Releases tremendous amounts of energy which the Earth receives as sunlight Is the energy source for our weather, waves and ocean currents 2. Radioactive decay The fission (breaking down) of large elements within the Earth, releasing tremendous energy Results in convection currents in the mantle, driving the plates against each other, and causing the land to rise up out of the ocean Earthquakes and volcanoes are associated with this Assignment • Complete Questions #5-7 on pg. 19 • Answers can be found in the notes or on pages 16-18