When Apollo astronauts first visited the moon, they brought back something somewhat expected (though predicted by Heinlein in Rocketship Gallieo) a gorgeous view of our little “blue marble” poised all alone in space.
Nothing will ever match the poignancy of that image, but as technology has improved, we’ve given it some competition.
This image, was used as wallpaper on the Apple iPhone until 2012:
But this is not a photograph of Earth. At all.