I have always like the picture of the pale blue dot. It really makes you think. Archive: https://archive.today/8O2uH From the post: >>On St Valentine’s Day 1990, NASA’s engineers directed the space-probe Voyager 1 – at the time, 6 billion kilometres (3.7 billion miles) from home – to take a photograph of Earth. Pale Blue Dot (as the image is known) represents our planet as a barely perceptible dot serendipitously highlighted by a ray of sunlight transecting the inky-black of space – a ‘mote of dust suspended in a sunbeam’, as Carl Sagan famously put it. But to find that mote of dust, you need to know where to look. Spotting its location is so difficult that many reproductions of the image provide viewers with a helpful arrow or hint (eg, ‘Earth is the blueish-white speck almost halfway up the rightmost band of light’). Even with the arrow and the hints, I had trouble locating Earth when I first saw Pale Blue Dot – it was obscured by the smallest of smudges on my laptop screen.