Mr. Longoria's Earth Science

Navigation is the science of identifying positions on Earth.  Ancient mariners and explorers, as well as travelers today, determine the latitude of any location north of the equator by measuring the altitude of Polaris (north star) above the horion.  For example, the latitude of New York City is approximately 41° north of the equator, so the angle of altitude of Polaris above the horizon is 41°. Our next topic of discussion and learning is determining the bases of our system of time on Earth.  Basically, we base our system of time on observations of the sun.  Noon (mid-day) is defined as th time the sun reaches the highest point in the sky.  The day is divided into 24 hours because that is the time it takes for the Earth to do one full rotation.  You can calculate your approximate longitude if you know the present time at the prime meridian of Greenwich and your local time.  To find longitude, you must first determine the difference in...

This week's focus is on the geo-coordinate system. We will learn how to locate exact positions on the surface of the Earth through the use of a grid system.  This grid ( coordinate) system assigns two numbers called latitude and longitude to every position on Earth. These coordinates (latitude and longitude) pinpoint the location on a grid of imaginary lines and gives each location a unique and unchangeable address. The latitude and longitude system has two reference lines: the Equator and the Prime Meridian.  The Equator is an imaginary line that circles the Earth half way between the North Pole and the South Pole.  Angular distance in degrees north or south of the Equator is latitude .  Angular distance in degrees east or west of the Prime Meridian is longitude . Homework : Due Wednesday, December 1, 2010 Textbook: read chapter 3.1, pages 46-47. Do questions 2 and 5 Review Book: read chapter 1, pages 20-21.