The Earth 367 12.1 The Earth As a Planet 368 Shape and Size of the Earth 368 Composition of the Earth 370 Density of the Earth 370 Extending Our Reach: Measuring the Earth's Mass 371
12.2 The Earth's Interior 371 Probing the Interior with Earthquake Waves 371 Heating of the Earth's Core 374
12.3 The Age of the Earth 376 12.4 Motions in the Earth's Interior 377 12.5 The Earth's Atmosphere 380 Composition of the Atmosphere 381 Origin of the Atmosphere 381 The Ozone Layer 383 The Greenhouse Effect 384 Structure of the Atmosphere 384
12.6 The Earth's Magnetic Field 385 Origin of the Earth's Magnetic Field 386 Magnetic Effects in the Upper Atmosphere 386
12.7 Motions of the Earth 388 Essay 2 Keeping Time 395 |