In late 1980, the Voyager 1 spacecraft had completed its primary mission to explore Jupiter and Saturn and was continuing forward, heading out of the solar system towards interstellar space. Before it turned away from Earth forever, the astronomer Carl Sagan, sensing a unique opportunity, asked NASA to turn one of the spacecraft’s cameras towards Earth to take an image. NASA engineers refused. They were concerned an attempt to image Earth might damage the camera if it accidentally aimed at the Sun.
After ten years of further consideration, instrument calibration, and setbacks caused by layoffs and reassignments of key personnel, the NASA administrator and former astronaut Richard Truly gave the go ahead to turn Voyager 1’s high-res camera towards the inner solar system to grab an image of Earth, Venus, Jupiter, and Saturn, and outward to image Uranus and Neptune. In the resulting color image, Earth occupied less than one of 640,000 pixels. The tiny speck of Earth in the image was nearly overwhelmed by sunlight scattered by the camera’s optics. The image was taken 25 years ago on February 14, 1990.
This image became known as the ‘pale blue dot’. Sagan later wrote a book inspired by the image entitled, Pale Blue Dot: A Vision of the Human Future in Space. In the book he expressed his views on the importance of this image and the perspective it gives us. His famous words have been incorporated into many videos, including the fine effort in the video at the top of the page.
Voyager 1 was 40.5 AU– about 6 billion kilometers– from Earth when it took this image. It took some five and a half hours for the data to reach Earth. The spacecraft left the solar system and entered interstellar space on August 25, 2012 when it crossed the heliospause, the boundary where the solar wind is no longer strong enough to push against the interstellar medium.
Voyager 1 is still going. It’s now about 130 AU from Earth (19.5 billion km), more than three times the distance to Pluto.