[rexreed]

Who would take a picture of the entire earth as a single image at one time?

Take that 500 Trillion Square Meters and divide it up by 1000 satellites (or whatever Starlink plans) and take images sequentially rather than all at once and it becomes rapidly much more manageable.

You don't need a single mult-terapixel image. You just need lots of much smaller images covering more territory on a continuous basis.

if you wanted pictures of the entire earth every 20 minutes, you'd need to figure out how many satellites would give you that coverage, the amount of resolution per image, and the bandwidth requirements transportation of those images in parallel.

Realistically, to get whole-earth coverage every 20 minutes would require a very large constellation of satellites. It's much more reasonable to get some less-than-100% coverage of the earth on a less-than-every-20-minute schedule and scale up from there.