JC010: Mud volcanoes and submarine canyons
Using Google Earth to track the ship's progress
Where are we?
You may have noticed that since the start of Leg 3 we have been including Google Earth co-ordinates in our blog entries. “Why have you been doing this?” you may ask.
Well, if you are familiar with Google Earth, then you may have realised that if you copy and paste the co-ordinates into the ‘Fly To’ box then it will ‘fly’ you straight in to our current location. If you put in the co-ordinates from each day then you can build up a picture of our journey. You can then go to ‘add path’ and draw lines between the co-ordinates to show the path of the RRS James Cook! Check out the following visual instructions.
How does this work?
Over the years, mapping techniques and means of our orientation in the world have become much more sophisticated. There are some fantastic resources already on this website about navigation at sea - read them to find out more.
Although the officers of RRS James Cook still need to be able to read and interpret charts (the name used for ‘sea maps’), the ship relies heavily on global positioning satellites (GPS) to tell it where it is going and how to get there. GPS units can tell you where you are, as they send out a signal to satellites which then ‘talk’ to a receiver in the GPS unit, using information on latitude and longitude to find the correct place on a virtual map.
Latitude and longitude are angles, measured in degrees (also written °), which you should have heard about in maths. If you look at a globe, lines of longitude run from top to bottom whilst latitude run round the earth . The degrees can be split up even further, into "minutes" ( ' ) and "seconds" ( " ). So if your longitude is 39 degrees, 34 minutes and 3 seconds, it is written 39° 34' 3"(on board the ship, the ' is replaced by a . and the " by nothing, so it looks like this: 39°34.3 . Google Earth uses the same measurements, but again you have to write them slightly differently it only understands them in a certain format. Incidentally, Google Earth’s images were compiled by a technique very similar to one (photo mosaicking) which is used to visually map the sea bed and has been carried out on the RRS James Cook. Check back for updates as an article on this will appear soon.
Why don’t you go back through the daily blogs for legs 1 and 2 of the cruise, input the co-ordinates into Google Earth and try to map out the entire journey of the RRS James Cook for this expedition? Don’t forget, you will have to use the format that Google Earth understands.
You could also find out more about the geographical features in the areas we pass, or about GPS.
The minutes and seconds used in measuring latitude have the same names as the minutes and seconds that make up an hour BUT they are completely different!
Any questions? Ask us using the question and answer page