Focus: Latitude and Longitude: The Earth’s Coordinate System Earth Science: Measuring Earth

Learning Objective By the end of today ’s class students should be able to determine and measure latitude and longitude.

Latitude Distance in degrees north or south of the equator (0°) If you Draw a line from any point on the Earth ’s surface to the center of the Earth, the angle that line makes with the equator will be that location ’s latitude.

Parallels of Latitude 90°N 30°N Parallels of 15°N latitude 15°S 30°S

lATITUDE Quick Review of Latitude and Longitude Measured in degrees North and South of the Equator. Lines drawn parallel to each other running west to east.

Longitude Distance in degrees, measured east or west, of the Prime Meridian (0°). Meridians are imaginary semicircles that converge at the poles. The maximum longitude is 180°

Meridians of Longitude °W °E

LONGITUDE Quick Review of Latitude and Longitude Measured in degrees East or West of the Prime meridian. Lines drawn running North and South

Writing latitude and longitude From USGS Maps : The latitude of White Plains, New York is about 41.06°N or Just… 41.1° N The longitude of White Plains, New York is about 73.76°W or Just 73.8°W The coordinates of WPNY are written 41.1°N Lat, 73.8°W Long Latitude is always (usually) written first Longitude is always written(usually) second

Writing latitude and longitude Latitude is always (usually) written first Longitude is always written(usually) second EX. 30.5° S 78.9° W

Complete the following in your notebook: Latitude = 5°N, Longitude = 176°W 5°N Lat, 176°W Long Latitude = 81°S, Longitude = 2°E 81°S lat, 2°E Long

Where in the World 5°N, 176°W 41°N, 73°W 81°S, 2°E

Latitude above Equator using Polaris The altitude of Polaris (height above your feet in the sky) equals the Latitude of where you are at (only in the Northern hemisphere), North Star is Polaris. The position of Polaris (angle of elevation) is fixed throughout the night The altitude of Polaris is equal to the observers latitude. OR you can say…… Angle of Elevation = Latitude on Map

Polaris/North Star Polaris is overhead at 90°N (The North Pole) Polaris is at the horizon at The Equator

Measuring Latitude 41ºN What is the astronomers latitude?? = 41º Zenith: Point in the sky directly above the observer

Measuring Longitude Have to know: The solar (clock) time at the Prime Meridian (Greenwich, UK) • Called Greenwich Mean Time (GMT) Local Solar Time (clock) is the time at your location. Such time, called mean solar time • Look at your watch or a clock

Celestial HEMISPHERE Altitude of Polaris is ? 50º

Movie about Northern Sky http://player.discoveryeducation.com/inde x.cfm?guidAssetId=E4323B12-6BF2-42E0- 9196- BD97E1F29643&blnFromSearch=1&produ ctcode=US Also, http://www.onr.navy.mil/focus/spacescien ces/skyobserve/constellations4.htm

Measuring Longitude Step 1: Calculate the time difference, in hours, between local clock time and the Greenwich time Step 2: Multiply this time difference by 15° Step 3: Determining Longitude: EL WE EL - East Later WE - West Earlier

Why Multiply by 15°?? The Sun moves across the sky (It’s really the earth turning)at a rate of 15° per hour. 15° = 1 hour

Measuring Longitude example Greenwich Time = 5:00 PM Local Time = 12:00 PM Time Difference = 5 hours ** Is local time earlier or later than Greenwich Time, are you east or west of the Prime Meridian?? EL WE Multiply ˘ 5 * 15° = 75°W

Movie bout Longitude http://www- c.pbs.org/wgbh/nova/longitude/find/ (www-c.pbs.org/wgbh/nova/longitude/find/)

Summary: Latitude Latitude is measured in degrees north or south of the equator. To find the latitude of a location you have to determine whether that location is north or south of the Equator!

Summary: Longitude Longitude is measured in degrees east or west of the Prime Meridian. To find the longitude of a location you have to determine whether that location is east or west of the Prime Meridian!

Measuring Latitude Using Polaris Latitude = Altitude of Polaris Polaris (The North Star) is only visible in the? Northern Hemisphere Ex. The altitude of Polaris is 78°. What is your latitude? 78°N