The Blue Marble photo, though, has proven to be the crew’s best known legacy. NASA released the image on Saturday, December 23, 1972, and it made the front page of most newspapers over that long ...

But while “Blue Marble” didn’t create an overnight revolution, it came to play an important role in the growing environmental movement. The first Earth Day had been celebrated on April 22, 1970.

But while "Blue Marble" didn't create an overnight revolution, it came to play an important role in the growing environmental movement. The first Earth Day had been celebrated on April 22, 1970.

Taken 50 years ago on Wednesday, the “Blue Marble” has become one of the world’s most widely reproduced photographs — and an icon of the environmental movement.