Your home, at night

Here's a picture I received in mail some time back. Its a collage of satellite images of various parts of Earth taken at night. Its a collage because all parts cannot have night at the same time. Looks beautiful ... and bluish. And here I was thinking the color of night is black. Well, the satellites have proved me wrong ;-).

You can tell major population areas by looking at concentration of lights. US eastern seaboard is clear, so is Japan, UK and western Europe. There's subtle concentration around Rio de Janeiro in Brazil as well as Johannesberg in South Africa. You can also clearly mark Sydney, Canberra, Melbourne and Perth in Australia, Bangkok in Thailand and HongKong in China. And notice how the Nile river is suspiciously marked bright in Egypt (Africa) ... I wonder why.

In India the lights are quite uniformly spread, but you can still distinguish Mumbai and Delhi.