Transcript Navigation
Navigation TWO SAD JOKES • Who leaves the table after everyone’s eaten? – A cannibal. • Why is the banana the most popular fruit? – Because it has appeal. How do we know where we’re at? X You are here. Huh? Before GPS…. Celestial navigation • The pattern of stars and planets seen from Earth are constant in space. The celestial sphere. • It is useful to be able to precisely specify positions on the celestial sphere. So, a set of coordinates is used that is similar to latitude and longitude on the Earth. The system of latitude and longitude was first suggested by Hipparchus, a Greek astronomer in the 2nd C. B.C. • The North Celestial Pole is the point on the celestial sphere directly above the Earth's North Pole. Similarly, the South Celestial Pole is directly above the Earth's South Pole. • The star Polaris, in the constellation Ursa Minor, is located very close to the North Celestial Pole. Polaris is therefore also called the North Star. More accurate: Longitude & Latitude Longitude: Angular distance on the earth's surface, measured east or west from the prime meridian at Greenwich, England. • Lines of longitude are blue (east) and red (west) in the drawing. Latitude The distance north or south of the earth's equator. 0 degrees latitude is the equator, the "belt" that goes around the "waist" of the earth. 90 degrees north is the North Pole and 90 degrees south is the South Pole. • Lines of latitude are blue (north) and red (south) in the drawing. Tools of the trade… • Sexton: measures the angle between celestial bodies and the Earth to determine position. • Compass: Point to magnetic North, so you can follow a course by knowing our position in relation to North. • Loran C: radio transmissions from set positions on the surface of the Earth, that triangulate to give you a position. • GPS: is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. Sexton • a device that measures the angle between two objects. It uses the position of stars to find it’s latitude, longitude. Compass Loran C • LORAN-C was originally developed to provide radio-navigation service for U.S. coastal waters and was later expanded to include complete coverage of the continental U.S. as well as most of Alaska. Twenty-four U.S. LORAN-C stations work in partnership with Canadian and Russian stations to provide coverage in Canadian waters and in the Bering Sea. LORAN-C provides better than 0.25 nautical mile absolute accuracy for suitably equipped users within the published areas. What is Loran-C? • Loran-C is a low frequency/long wave electronic position fixing system using radio signals transmissions @ 100 KHz from 3 or more transmitters, linked in a chain. It gives a latitude and longitude readout position to marine, aero and land receivers. The Global Positioning System (GPS) • is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. • GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter! • In a sense it's like giving every square meter on the planet a unique address. • GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. And that makes the technology accessible to virtually everyone. • These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, even laptop computers. Coordinates given in Longitude, Latitude West East Longitude: 40 E Latitude: North South 65 N Mapping activity • http://olc.spsd.sk.ca/DE/k9mod/Mapskill/m od3fl5.swf