How does Google Earth work?

The last time you got lost, how did you get home? Did you text a friend? Did you call a taxi? Most people would just use Google Maps. But how many know how it works?

Google Maps was developed by two Danish brothers Jens and Lars Rasmussen and was launched on February 8, 2005. It is a mapping site that gives the viewer a 360° view of what is going on in our planet.

At the heart of it all is a satellite in a low orbit, going from one pole to the other. It’s different from geostationary communications satellites because it’s at 20,000 miles and always above the equator.You can’t get a decent shot from that height and the angle is extremely limited.You’d never get a straight down shot the only alternative is to use a camera inside a satellite that’s swooping from pole to pole at a much lower height, typically about 300 miles.

The camera is unique, not like a DSLR/Digital Single Lens Reflex that exposes all the pixels at once. There’s no shutter the camera is designed more along the lines of a flatbed scanner hooked up to a very very long telephoto lens. As the satellite floats along the image of the earth in effect moves beneath it.

The lens itself is gigantic imagine a telephoto lens 30 feet long! That’s 8.8 meters. It has a fixed aperture of f(Feet)/14.7, kind of slow but they always shoot in the daytime and of course, only on sunny days typically they shoot with the sun at an angle to give better definition. They can even make 3D shots by combining images shot at an angle.

The camera can point up to 20 degrees from vertical.You might be thinking how do you fit a 30-foot lens inside a satellite? The engineers at DigitalGlobe call it “folded optics” lots of mirrors bouncing the image back and forth. The camera produces an image that’s generally rectangular 16 km wide and 250 km long. That’s roughly 10 miles by 155 miles. But remember that’s the size of the image not the size of the sensor. The sensor is basically just a slit. Theoretically, they could shoot a continuous strip around the entire earth. But there’s not enough storage space on board for that much data, so they cut it off at 155 miles.

So to sum it up Google Maps is a computer program that renders a 3D representation of Earth based on satellite imagery it maps the earth by superimposing satellite images aerial photography and GIS(Geographic information system) data onto a 3D globe allowing users to see cities and landscapes from various angles. Users can explore the globe by entering addresses and coordinates or by using a keyboard or mouse. The program can also be downloaded on a smartphone or tablet using a touchscreen or stylus to navigate.

It is a great app/website and I recommend you try it. So the next time you are lost, you won’t need to call a friend. Just search (Google Maps).

— Pepper (G6A)

Sources used: (for featured image)


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  1. aanchalangelchand says:



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