When people and robots launch into space on far-off missions, it's a quiet tradition to briefly turn back toward Earth and take a photo.
These rare views of our home planet — recorded from hundreds, thousands, millions, or even billions of miles away, often with outdated cameras — are rarely as crisp or colorful as the smartphone images we snap today on terra firma.
But the exceptional perspective they afford more than compensates for any visual shortcomings.
Photos of Earth from space not only help scientists understand how a habitable world looks from afar, helping the search to find more cozy planets, but also remind us of a humbling and chilling truth: We live on a tiny, fragile rock that is hopelessly lost in the cosmic void.
Here are 25 of the most arresting images of Earth and the moon from space that humankind has ever captured. (We recommend viewing this post on a desktop computer.) :