Being a navigator is all about reading maps, identifying location and direction, understanding topography & terrain, creating trails and navigation
Welcome to the first part of our 11 part course. All parts are designed to be hands on so that you can understand the required topics practically through hands-on both at home and in the field
Type: home assignment
Date: Friday 13 Feb
Deadline: Tuesday 17 Feb
Duration: 1-2 hours
Submit one set of answers per team
All team members to participate
Open Google Earth on your laptop
A 3D view of our planet will be shown
You can move the globe in different directions with your mouse
Goto menu View - Grid
A grid will now be displayed across the globe: horizontal circles (latitude) and vertical circles (longitude)
Each location on our planet is uniquely identified by the intersection of two circles: the longitude and latitude
Longitudes connect both poles (North, South) and cut the equator vertically
The equator encircles the Earth 360 degrees (full circle)
The "zero" longitude or "Greenwich Meridian" is the vertical circle which runs through London.
Vertical circles right of the "Greenwich Meridian" are called Eastern longitudes: most of Europe and Asia (0 to 180 degrees East)
Left are the Western Longitudes: the Americas (0 to 180 degrees)
(move the globe horizontally with your mouse to see all Eastern and Western longitudes)
Latitudes are horizontal circles which run in parallel with the Equator
The "zero" latitude corresponds to the Equator
From North to the South pole there are 180 degrees (half circle)
The horizontal circles above the equator till the North pole are called Northern latitudes (0 to 90 degrees)
The ones below the equator till the South pole are called Southern latitudes (0 to 90 degrees)
(move the globe vertically with your mouse to see all Northern and Southern latitudes)
Every location on our planet is uniquely identified by the intersection of one vertical and one horizontal circle
This is called the latitude and longitude of that location
Let's take for example Chennai city
Move the globe with your mouse till you see India and Chennai
Chennai is cut by following two circles:
* Vertical circle (Longitude) 80 degrees right or East from Greenwich Meridian or Prime Meridian
* Horizontal circle (Latitude) approximate 13 degrees above or North of the Equator
So Chennai's location is uniquely identified as Longitude 80 deg East and Latitude 13 deg North
(Move the globe with your mouse to see Chennai and check the intersecting longitude and latitude)
Degrees, Minutes, Seconds
Degrees are very large: the perimeter of our planet is 40 thousand kilometers (along the Equator)
This corresponds to 360 degrees which means 1 degree is equal to approx 111 kilometers or 60 miles (nautical miles: 1 mile = 1852 meters)
To fix a location more accurately every degree will be divided into 60 minutes: 1 minute = 1 mile
And every minute will be further divided into 60 seconds: 1 second = approx 31 meters
Use your mouse to zoom further into the Global into Chennai: let's find the unique location of the Cricket Stadium near Marina beach
Zoom in until you can see the stadium: it's a white circle right off Marina.
It's location is nearby the intersection of two lines:
Longitude: 80 deg 16 min 48 seconds East
Latitude: 13 deg 03 min 54 seconds North
You can identify the exact location of the Cricket Stadium by dropping a yellow pin:
Longitude: 80 deg 16 min 45 sec
Latitude: 13 deg 3 min 46 sec North
(Try it yourself)
Similarly, distance between two locations can be measured in seconds, minutes and degrees
For example let's check the distance between the Cricket Stadium and the Marina Lighthouse
The Cricket stadium is located near latitude North 13 deg 03 min 54 sec
The Lighthouse is near latitude North 13 deg 02 min 24 seconds
Every horizontal latitude line shown in the grid below is 18 seconds or approx. 560 meters (1 sec = 31 meters)
The distance between both is 1 minute and 30 seconds
This corresponds to 1 mile (1 mile = 1852 meters) and 30 seconds (1 sec = 31 meters) or approx 2.782 meters
You can measure the exact distance in Google Earth through the Ruler tool
Click on the Stadium and next click on the Lighthouse
Distances is 2565 meters (less than first approximation above as the Cricket Stadium is actually lower then the N 13 03 54 latitude line)
(Try it yourself)
Do it yourself - Home Assignment #1
Now it's time to your hands dirty ! Go through the practical assignments below to validate your understanding of latitudes and longitudes, the fundamental basis on which navigation will work.
Question 1 - what's the location (longitude, latitude) of the (center of) "Ottiyambakkam Lake"
(Search on name in Google Earth top-left search box)
(Drop a yellow Pin to identify lat, lon)
Question 2 - what's the location of the (center of) quarry in Ottiyambakkam?
(Located a bit Northwest of the lake)
(Drop a yellow Pin)
Question 3 - what's the difference (distance) in longitude (East-West) between both locations in seconds?
Question 4 - what's the corresponding approx. longitudinal distance in meters?
Question 5 - what's the difference (distance) in latitude (North-South) between both locations in seconds?
Question 6 - what's the corresponding approx. latitudinal distance in meters?
Question 7 - what's the direct line distance between both in meters?
(Use Google ruler tool)
Question 8 - what's the location (longitude, latitude) of your residence in Chennai?
Question 9 - what's the name of the nearby main road?
Question 10 - what's the nearest direct distance from your residence to main road (either latitude or longitude)?
(Sample: Lon 13 sec)
Submit your answers (one per team, not individually) through this form