Bell Question Define the following terms: 1. Rotation 2. Revolution 3. Precession 4. Nutation Answer the following question: 5. What would happen if the Earth’s axis were not tilted 23.5. (If it were straight up and down.)

Grid System and Time

Latitude Distance north or south of the equator Distance north or south of the equator Equator = 0° latitude Equator = 0° latitude

Longitude Distance east or west of the Prime Meridian Distance east or west of the Prime Meridian Prime Meridian = 0° longitude ; passes through Greenwich, England Prime Meridian = 0° longitude ; passes through Greenwich, England

Greenwich, England 0° Longitude (Prime Meridian)

Example What city is located at 37°S and 144°E? What city is located at 37°S and 144°E?

Answer Melbourne, Australia

Example What city is located at 40°N and 105°W? What city is located at 40°N and 105°W?

Answer Denver, Colorado

Distance Between Lines of Latitude 69 mi/° * Difference in Degrees of Latitude

Example Calculate the number of miles between Atlanta (33°N, 84°W) and New York City (40°N, 74°W). Calculate the number of miles between Atlanta (33°N, 84°W) and New York City (40°N, 74°W).

Answer Diff in Latitude = 40°N - 33°N = 7° Diff in Latitude = 40°N - 33°N = 7° 69 mi/° * 7° = 483 miles 69 mi/° * 7° = 483 miles

Distance Constant How many miles are there in 1° of longitude at the equator given that the circumference of the earth is 24,860 miles and that there are 360° in a circle? How many miles are there in 1° of longitude at the equator given that the circumference of the earth is 24,860 miles and that there are 360° in a circle? 24,860 mi = 69 mi/° 360° 360°

Distance Between Lines of Longitude 69 mi/° * Difference in Degrees of Longitude * Cosine of Parallel Traveled

Example Calculate the number of miles between Cairo (30°N, 31°E) and New Delhi (28°N, 77°E). Assume travel along the 29°N parallel. Calculate the number of miles between Cairo (30°N, 31°E) and New Delhi (28°N, 77°E). Assume travel along the 29°N parallel.

Answer Diff in Longitude = 77°E - 31°E = 46° Diff in Longitude = 77°E - 31°E = 46° 69 mi/° * 46° * Cos(29°) = 2,777 mi 69 mi/° * 46° * Cos(29°) = 2,777 mi

Time Zones How many degree of longitude are there in one hour (one time zone) given that there are 360° in a circle and 24 hours in a day? How many degree of longitude are there in one hour (one time zone) given that there are 360° in a circle and 24 hours in a day? 360° = 15° 24 h 1 h

Time Zones Standard time zones are spaced 15° apart Standard time zones are spaced 15° apart For every 15° you move west, subtract one hour of time For every 15° you move west, subtract one hour of time For every 15° you move east, add one hour of time For every 15° you move east, add one hour of time

Example If it is 12 PM in Waterloo, Iowa what time is it in Springfield, Massachusetts? If it is 12 PM in Waterloo, Iowa what time is it in Springfield, Massachusetts?

Answer 1 PM 1 hour difference, move east, so add 1

International Dateline The 180° longitude parallel The 180° longitude parallel

International Dateline When you move west across the dateline, it is one day later When you move west across the dateline, it is one day later When you move east across the dateline, it is one day earlier When you move east across the dateline, it is one day earlier The relationship between direction traveled and time does not change (move west – one hour earlier; move east – one hour later) The relationship between direction traveled and time does not change (move west – one hour earlier; move east – one hour later)

Example If it is 1 PM in Juneau, Alaska on June 12, what time and day is it in Tokyo, Japan? If it is 1 PM in Juneau, Alaska on June 12, what time and day is it in Tokyo, Japan?

Answer 7 AM ; June 13

Time, Distance, and Speed Combination Problems Departing Washington, DC (33°N, 77°W) at noon, [at what speed] would you have to travel in order to land in Denver, CO (39°N, 105°W) precisely at noon? Assume travel along the 35°N parallel. Departing Washington, DC (33°N, 77°W) at noon, [at what speed] would you have to travel in order to land in Denver, CO (39°N, 105°W) precisely at noon? Assume travel along the 35°N parallel.

Answer 105°W - 77°W = 28° (Diff in Long) 105°W - 77°W = 28° (Diff in Long) D = 69mi/° * Cos(35°) * 28° = 1,582 mi D = 69mi/° * Cos(35°) * 28° = 1,582 mi S = D/T = 1,582mi / 2h = 791 mph S = D/T = 1,582mi / 2h = 791 mph