PHYS 1055 Study Guide - Midterm Guide: Ecliptic, Equinox, Northern Hemisphere
Document Summary
Astronomical unit: earth"s average distance from the sun (150 million km) Light-year: distance that light can travel in 1 year (10 trillion km) 14 billion years ago the universe happened. Rotation and orbits: earth rotates from west to east (counterclockwise) which is why the. Sun and stars appear to rise in the east and set in the west each day: earth"s axis is tilted by 23. 5 so that it"s pointed at the north star. Constellation: a region of the sky with well-defined borders: 88 official constellations. Seasons: the tilt of earth"s axis causes sunlight to fall differently on earth at different times of year. Moon rotates once in the same amount of time it takes to orbit earth once. Models: conceptual representation created to explain and predict observed phenomena: geocentric model: thales, aristotle, ptolemy, ptolemaic model: ptolemy"s geocentric model to distinguish it from earlier geocentric models.
