Lecture 14 Outline of Last Lecture I. Earth A. Layers B. Atmosphere Outline of Current Lecture I. The Earth’s Atmosphere A. Layers B. Magnetic Field C. Electric Field II. The Moon Current Lecture I. The Earth’s Atmosphere - Airglow: a glow in the night sky caused by caused by the collision of x-rays and charged particles from the Sun with atoms and molecules, especially of oxygen, sodium, and the hydroxyl radical (OH). Steadily diminishes throughout night. - Twilight glow: a dim light from the upper atmosphere caused by emissions from atoms and molecules ionized by solar radiation. A. Layers (from closest to furthest) - No Electric Charge - Troposphere: Closest to Earth; All weather occurs - Stratosphere: Constant temperature, calm - Ozonosphere: Important for our survival; Absorbs UV radiation - Electric Charge - Ionosphere: Electrically charged, reflects radio waves - Exosphere: Particles are in independent orbits about the Earth - Magnetosphere: region controlled by Earth’s magnetic field o Van Allen radiation belts o Inner belt: made of protons o Outer belt: electrons, unstable B. Magnetic Field 1. Main: Fluid metals of motion in the core, 80% of field 2. Residual: Deposits of metallic materials in crust (mostly iron and nickels), 15% 3. Atmospheric: rise/fall of Ionosphere, 1-5% of field C. Electric Field 300,000v difference between ionosphere and Earth. Lightning and electrical discharge toward Earth when charge separates II. The Moon - Sidereal Period: 27.3 days ASTR 1010 1st Edition- Synodic Period: 29.1 days - Synchronous orbit motion: Moon’s rotation is synchronized with orbital motion. - We see 59% of the moon because: - Lunar libration: A very slow oscillation, real or apparent, of a satellite as viewed from the larger celestial body around which it revolves. - Latitude libration: north and south rocking of the moon. Tilt of moon’s orbit with respect to equator - Longitude libration: East and West rocking. Elliptical
View Full Document
Unlocking...