@earth_pics on twitter and pics_earth on instagram post many gorgeous and interesting photos from around the world every day, but I can't see any attribution given, and they didn't answer me when I tweeted them asking when the photos come from.

Does anyone know about these accounts and where they get their images from?

I'm not accusing anyone of anything, or trying to get my own images on there, I just find it weird that there's no credit at all given or much information about the accounts themselves.  I've seen images where I was genuinely interested to see who the photographer was but had no way of finding out.  You can save these images at about 800x600 too, not great quality but fine for web use.