[Music playing]

Screen shows a blue sky with clouds. Text on the screen reads, ‘Curriculum Secondary Learners – HSIE. Latitude and longitude. Presented by Melissa Ellis’.]

Melissa Ellis

Have you ever wondered how apps like WhatsApp can pinpoint exactly where you are or where your friends are? Or how planes can navigate in the dark?

[Presenter is standing in front of a decorative background. In the bottom right-hand corner of the screen, the text reads, ‘Melissa Ellis. HSIE Curriculum Support Project Officer’.]

It all comes down to latitude and longitude.

[Screen shows an animated illustration of a globe. The word ‘Longitude’ is written in a blue box, and the word ‘Latitude’ is written in a red box. While the presenter is speaking, a series of evenly-spaced lines appear on the globe, creating a grid. All of the vertical lines are blue and all of the horizontal lines are red. 13 dark blue dots appear in random spots on the globe.]

It's possible to locate any place on the Earth using an imaginary grid of lines called latitude and longitude.

[Screen slowly zooms in on one of the dots. The rest of the illustration fades to a lighter colour.]

These are simply invisible lines that go around the Earth, and the point at which they intersect gives a location.

[On the globe, everything fades away except for the red horizontal lines. Three of the lines towards the centre of the globe are dotted. They are also thicker than the others. The middle line has two labels. On the left of the globe, it is labelled, ‘West’. On the right of the globe, it is labelled, ‘East’.]

Latitude lines are parallel, lateral lines that circle the globe in an east to west direction. The most recognisable parallel of latitude is the equator.

[A white circle appears on the middle line. It is labelled, ‘Equator’. The northern hemisphere on the globe flashes blue and disappears. The southern hemisphere then does the same.]

This invisible line passes through the centre of the Earth and divides the northern and southern hemispheres.

[A vertical ruler appears from the equator. It gradually stretches out towards the north and south of the globe.]

The other lines of latitude measure how far south or north the point is from the equator.

Latitude is expressed in degrees.

[The ruler shrinks back towards the equator and disappears. In its place, a red box appears. It reads, ‘0 degrees’. A similar label appears on both the North Pole and the South Pole. They both read ’90 degrees’.]

The latitude of the equator is 0 degrees, the North Pole is 90 degrees and the South Pole is 90 degrees.

[The entire illustration blurs and fades to a lighter colour. On top of the faded illustration, the screen now reads, ‘Lat is flat’.]

To help you remember that latitude lines run across, try to remember – lat is flat.

[Screen returns to the globe illustration with the three dotted lines. The top line now has the text, ‘23.5 degrees north’. This line is labelled, ‘Tropic of Cancer’.]

So the latitude line at the Tropic of Cancer is 23.5 degrees north, as it is above the equator.

[The bottom dotted line now has the label, ‘Tropic of Capricorn’. It also has the text, ’23.5 degrees south’.]

The Tropic of Capricorn is 23.5 degrees south, as it is below the equator.

[All of the lines and labels on the globe disappear. Blue vertical lines begin stretching in equal intervals along the globe. One of the lines towards the right-hand side of the globe is dotted. It is also thicker than the others. Text on screen reads, ‘Longitude’.]

Longitude lines are the long lines that run from the North Pole to the South Pole.

[Underneath the word, ‘Longitude’, the word ‘Meridian’ appears.]

They are sometimes called meridians.

[A white circle appears on the dotted line. It is labelled, ‘Prime meridian’. A red arrow points to where England is located on the globe. This arrow is labelled, ‘Greenwich’.]

A very important line of longitude is the Prime Meridian that runs through Greenwich, England.

[On the left-hand side of the dotted line, a label appears that reads, ‘west’. On the right-hand side of the line, a label appears that reads, ‘east’.]

Longitude is measured in terms of how far east or west the point lies from the Prime Meridian.

[A blue label appears on every vertical line on the globe. These labels contain different measurements in degrees. The Prime Meridian is 0 degrees. The closer a line is to the Prime Meridian, the closer the measurement is to 0.]

This can vary between 0 and 180 degrees, east or west.

[Two points appear on the screen. Point A is on the right of the Prime Meridian. It is labelled, ‘45 degrees E’. Point B is on the left of the Prime Meridian. It is labelled ’15 degrees W’.]

This means that the longitude at point A is 45 degrees east, as it is east or to the right of the Prime Meridian. And the longitude at point B is 15 degrees west, as it is west or to the left of the Prime Meridian.

[Screen shows a map of Australia. The map is overlaid with a grid that shows the latitude and longitude. A circle appears in the centre of Australia. It is labelled, ‘Centre of Australia. 23 degrees and 50 minutes south. 135 degrees and 0 minutes east’. Screen zooms in to highlight this part of the map.]

When we put latitude and longitude together, we have the coordinates of a place. The point in the middle of Australia is 23.5 degrees south and 135 degrees east.

[The map on screen fades into the background. On top of the faded map, the screen now reads, ‘Latitude is always written before longitude’.]

Latitude is always written before longitude.

[Underneath the previous writing, the alphabet stretches across the screen. The letter ‘A’ and the letter ‘O’ are both placed in a red box. A dotted line connects the letter, ‘A’, to the word, ‘Latitude’. Another dotted line connects the letter, ‘O’, to the word, ‘longitude’.]

If you forget which comes first, think about which comes first in the alphabet – a or o.

[Screen shows presenter standing in front of a decorative background.]

Lines of latitude have about 111 kilometres between each. So to pinpoint exact locations, it is necessary to break these down further. Each degree of latitude and longitude can be further broken down into 60 minutes.

[Screen shows the previous map of Australia. A circle appears where Sydney is located. It is labelled, ‘Sydney’. Sydney’s latitude and longitude are written underneath the label. The screen zooms in to highlight this part of the map.]

For example, Sydney's latitude and longitude are given as 33 degrees 51 minutes south, 151 degrees 12 minutes east.

[The map on the screen fades into the background. On top of the faded map, an illustrated globe appears. The globe uses dotted lines to show where Greenwich, Sydney and the Equator are located in relation to each other.]

Meaning it lies 33 degrees 51 minutes south of the equator and 151 degrees 12 minutes east of Greenwich.

To get even more specific, each minute can be further broken down into 60 seconds.

[Screen shows a video of the Sydney Opera House. Text on the screen shows the latitude and longitude of the landmark.]

For example, the Sydney Opera House’s latitude and longitude are given as 33 degrees 51 minutes 30 seconds south, and 151 degrees 12 minutes 53 seconds east, meaning it lies 33 degrees 51 minutes and 30 seconds south of the equator and 151 degrees 12 minutes and 53 seconds east of Greenwich.

[Screen shows presenter standing in front of a decorative background.]

There you have it, latitude and longitude.

[Text on screen reads, ‘References. Storyblocks: aerial-panoramic-view-of-the-sydney-opera-house-by-the-harbour-bridge-april-10-2017-SBV-327188273-HD.mov’.

Text on the screen reads, ‘Acknowledgements. NSW Geography K-10 syllabus © NSW Education Standards Authority (NESA) for and on behalf of the Crown in right of the State of New South Wales 2015. See the NESA website for additional copyright information. NSW Department of Education Curriculum Secondary Learners. Southern Cross School of Distance Education.’

The screen shows an Indigenous artwork. The artwork features a landscape with native Australian animals. It is titled ‘Our Country’ by Garry Purchase. The text at the top of the screen reads, ‘Filming of these videos has taken place on Bundjalung land’. Video concludes by displaying the NSW Government logo.]

[End of transcript]