Earth Joins the Selfie Brigade


Remember when you had to rely on seeing just a part of yourself in the reflection of a dark lake or in a small expensive piece of polished copper or silver-mercury? Probably not. I know that I, for one, take the highly reflective and often inexpensive modern mirrors for granted, not to mention the panoply of high-resolution cell phone cams, web cams and other photography and video cameras that can show us what we look like from head to toe at any given moment. Kim Kardashian West offers perhaps a good example of how ubiquitous “selfies” can be today – so easy to access that she can post many dozens each week across her
On the calm top of a lake, a clear reflection is produced. Credit: Prabhu B Doss

If you go back just a handful of decades however, our home planet, Earth, was unable to get a full well-lit view of itself (and good lighting, as Kim Kardashian West knows, is everything). Earth is a pretty decent size for a terrestrial planet at about 4,000 miles in radius with a total surface area of about 200 million square miles. To get a good full-body shot of something that large, the camera taking the planet-sized selfie has to be far enough away from Earth to get the entire planet in the shot, which could be between about 25,000 miles and a million miles away. To achieve the best lighting conditions, the camera also has to be positioned in between the lighting source (our Sun) and the subject (Earth).

Having gone many thousands of years without humans being able to see their own whole planet, it is perhaps unsurprising how much of a hit the very first well lit, high-resolution, full-body views of Earth were. As the —> Read More