The First Blue Marble: This is the famous and iconic first photograph of the entire Earth lit by natural sunlight. The Apollo 17 crew took this photo on their final mission as they were traveling toward the moon in 1972. It was taken from 28,000 miles or 45,060 km away. This is the first time the Apollo trajectory made it possible to photograph the South polar ice cap.” December 7, 1972
Blue Marble Composite 2002: As a result of the challenges involved in taking a sunlit image of the entire Earth, space agencies most use composite images. “Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations of the land surface, oceans, sea ice, and clouds into a seamless, true-color mosaic of every square kilometer (0.4 square miles) of our planet.” Visualization date: August 2, 2002.
Blue Marble Composite 2002: High res 2048 x 2048 pixel version for desktop background
The Second Blue Marble 2015: On July 6, 2015, the Deep Space Climate Observatory satellite (DSCOVR), took the first full photograph of the sunlit Earth in 43 years- from 1.5 million km or one million miles away.”
It’s actually pretty difficult to capture the image of a fully illuminated Earth. The first problem is distance. You have to get much further away from Earth than our activities in outer space usually require. For example, the International Space Station only orbits at a height of just 400 kilometers, or about 249 miles away from Earth. Satellites in geosynchronous orbit can get some sweet views, but they can’t see the entire hemisphere.
The second problem is lighting. “In order to get a photo of the whole Earth lit entirely by sunlight, a person (or camera) must be situated in front of it, with the sun directly at his or her back. Not surprisingly, it can be difficult to arrange this specific lighting scheme for a camera-set up that’s orbiting in space at speeds approaching thousands of miles per hour.”
Here’s Obama tweeting it: https://twitter.com/potus44/status/623137065341952000?lang=en