Happy 21st birthday to APOD!

Why do we all love APOD so? How is it that APOD inspires so much affection that people volunteer to create mirror sites and translate APOD into many different languages, to run affiliated social media sites (including Facebook (Spanish, Portuguese), Twitter, G+, Instagram, Reddit, and tumblr), and create APOD apps and administer a discussion forum? That people stop by every day to look at the site? That it has fans all over the world?

That you are here indicates that you like APOD, too! Why? What do you like about the site? Please let us know in the comments below!