London and surroundings photographed from the International Space Station

© NASA

London and surroundings photographed from the International Space Station

Greetings, Earthlings! It’s World Population Day and to get you thinking about just how many of us there are walking around on this planet, take a look at this photo of London. As the International Space Station passed over the capital, all lit up during the night, a simple photograph shows how easy it is to see large human settlements and how our presence affects the space around us. Our current population is more than 7.4 billion and counting. The United Nations, founders of World Population Day, hope that the observance prompts conversations about how to keep life on Earth sustainable as our numbers increase.