Latitude and Longitude

Scientists have established a coordinate system using circular lines to pinpoint any place on the Earth. The first Coordinate system was used by Hipparchus between 190 and 120 B.C. This Coordinate System is based on lines of: Latitude: East/West parallel lines. Main reference line is the Equator. Longitude: North/South lines from Pole to Pole Main Reference line is the Prime Meridian

Latitude Known as Parallels. Equator - Line drawn around the Earth that is equidistant to each pole. Lines of Latitude are imaginary lines drawn around the Earth parallel to the equator. Equator = 0 degrees North Pole = 90  North Latitude South Pole = 90  South Latitude In the Northern Hemisphere, Latitude = the angular altitude of the North Star (Polaris) Also known as the Pole Star.

Latitude Continued The half of the Earth NORTH of the Equator has lines of North Latitude and is known as the Northern Hemisphere. The half of the Earth SOUTH of the Equator has lines of South Latitude and is known as the Southern Hemisphere.

Lines of Latitude Equator Tropic of Cancer 23.5  N. Tropic of Capricorn 23.5  S.

Latitude in the Northern hemisphere is determined by the altitude of the North Star… Polaris. Polaris is in the constellation Ursus minor, also known as, the little dipper Its name comes from the Latin, Stella Polaris, meaning "Pole Star." 90  60  30  00 Angle to Polaris

Polaris The angle to Polaris is equal to the Latitude… For Example, if we measured the angle to be 45  then we would be located at  North Latitude. Horizon Angle to Polaris

Finding Polaris and Ursa Minor To find the star Polaris and the constellation Ursa Minor, locate the two end stars in the cup of the "Big Dipper." Connect a line through these two stars. This will point to the star Polaris. Polaris is in the constellation Ursa Minor. Ursa Minor is better known as the "Little Dipper." Polaris will not be an extremely bright star, about the same brightness as the "pointer stars." Polaris is also known as the North Star because it is directly above the Earth's North Pole. This star is about fifty (50) light years away from Earth.

The Big Dipper

Longitude Lines of Longitude are known as Meridians. 0 degrees Longitude runs from Pole to Pole through the town of Greenwich England. This is the Prime Meridian. Maximum Longitude is 180 degrees and is opposite Greenwich England on the Earth. This is known as the International Date Line.

Longitude continued The half of the Earth WEST of Greenwich, England has lines of West Longitude and is known as the Western hemisphere. The half of the Earth EAST of Greenwich, England has lines of East Longitude and is known as the Eastern hemisphere.

Longitude continued Find the difference in hours between local time and Greenwich time. Multiply the difference by 15  per hour (The rate at which the Earth Rotates) If Local time is earlier than Greenwich time, then your position is West Longitude. If Local time is later than Greenwich time, then your position is East Longitude.

Prime Meridian Noon 1:00pm 2:00pm 11:00am 10:00am 15°

Examples There is a 5 hour time difference between New York City and Greenwich, England. What is the Longitude of NYC? (Local Time in NYC is earlier than Greenwich)

ANSWER 75  West Longitude

Try This One It is 10:00am at a point located 45° West Longitude. It is 2:00 pm at your location. What is your longitude?

Answer 15° East

One More It is 12 noon at the Prime Meridian. You are on a boat where it is 4:00 am. You look up at the sky and determine the altitude of Polaris to be 35°. What is your Latitude and Longitude.

Answer 35° N; 120 ° W