On December 7, 1972, the crew of the Apollo 17 spacecraft, on their way to the Moon, took a picture of Earth at a distance of about 29,000 kilometers. It has been named The Blue Marble and is one of the most reproduced images in history.
Five years later, in 1977, NASA launched the Voyager 1, to explore the outer solar system. It was a highly successful mission with flybys of Jupiter, Saturn and Titan, Saturn’s largest moon.
After completion of this primary mission and before leaving the Solar System, it was suggested by astronomer and author Carl Sagan, that the Voyager 1 should look back and take one last picture of Earth. This picture was taken on February 14, 1990 at a distance of about 6 billion km from Earth. The picture has been named the Pale Blue Dot , because in this picture Earth is not more than a single pixel. You may have to click on the picture to enlarge it and see Earth more clearly. The coloured bands are artefacts, caused by reflection of sunlight in the camera.
Inspired by this picture Sagan wrote the book Pale Blue Dot in 1994. Here is a quote from this book:
Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.
I have used the Blue Marble image for a long time as background on my monitor screen. Recently I have changed it to the Pale Blue Dot.
At the moment Voyager 1 is still (partly) operational at a distance of about 22 billion km from the Sun, speeding away at more than 60.000 km/h.