20 images that show how much we've reshaped planet Earth in the past 70 years

April 22 is Earth Day, a world holiday celebrating our planet - the only home we've got (so far).

Humans have had an unmistakable impact on Earth - one that pops out in sharp relief when you look at this collection of images comparing what specific areas look like now to how they appeared in the past.

In some cases, the images (mostly from NASA, unless otherwise noted) were taken as far as 50 years apart; in other cases, they were snapped with just 10-15 years in between.