Movements of the Earth Chapter 26.2

Rotation vs. Revolution  Rotation = The spinning of the Earth on its axis.  This is what gives us our days.  Revolution = Motion of a body that travels around another body in space; complete revolution around the sun takes 365 ¼ days (1 year).

Evidence of Earth’s Rotation  Foucault Pendulum: Path of pendulum changed through out the day  Coriolis effect = Caused by rotation; creates the curvature of wind belts & ocean currents.  Position of constellations

Earth’s Orbit  Orbit = the path that a body follows around another body in space  Earth’s orbit around the sun is not a circle but rather an ellipse.  Since it’s an ellipse – Earth is not always the same distance from the sun  Perihelion --- point when it’s closest to the sun  Aphelion – point when it’s the farthest from sun

Constellations  Constellations – group of stars that are organized in a recognizable pattern.  Evidence for revolution – Over a period of several weeks has a different position in the night sky; the night side of Earth faces a different direction of the universe.  Causes different constellations as the season changes.

Measuring Time  Formation of the calendar – System for measuring long intervals of time; divided into periods of days, weeks, months, and years. (Egyptians, Babylonians, Aztecs).  Modern Calendar – Created a calendar that aligned with the seasons (Gregorian calendar)  Time Zones – 24 standard time zones; noon is the determining factor (sun is the highest in the sky)  International date line – A line that runs N-S through the Pacific Ocean; doesn’t cut through continents or islands.  Daylight savings time – take advantage of the daylight

The Seasons  Axis tilt – 23.5° -- this remains the same throughout the Earth’s orbit