Pale Blue Dot is the name given to a photograph of planet Earth taken on 14 February 1990 by Voyager 1, a robotic explorer built by NASA’s Jet Propulsion Laboratory. In the photograph, taken from a record distance of about 6 billion kilometres, Earth's apparent size is less than a pixel. The planet appears as a tiny dot against the vastness of space, among bands of sunlight reflected by the camera. The phrase "Pale Blue Dot" has come to represent a contemplative perspective on humanity's relationship to the cosmos.

The spacecraft had flown past Jupiter and Saturn and sent beautiful close-ups and exciting scientific data back to Earth. After Saturn, the spacecraft was destined to spend its remaining years in deep space. There would be nothing but darkness, punctuated occasionally by the twinkle of distant stars. There was no reason to keep Voyager’s cameras on for that, and NASA wanted to conserve the spacecraft’s power. But, before turning the cameras off, NASA engineers directed Voyager to turn around and take one last look at home, at the request of astronomer and author Carl Sagan.

Sagan acknowledged that such a picture would not have had much scientific value, as the Earth would appear too small for Voyager's cameras to make out any detail, but it would be meaningful as a perspective on humanity's place in the universe.

The phrase "Pale Blue Dot" was coined by Sagan in his reflections on the photograph's significance, documented in his 1994 book of the same name. In the book Carl Sagan comments on what he sees as the greater significance of the photograph, writing:

“From this distant vantage point, the Earth might not seem of any particular interest. But for us, it's different. Consider again 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.”

Hear it spoken by Sagan in this video.

In 2020, for the image's 30th anniversary, NASA published a new version of the original Voyager photo: Pale Blue Dot Revisited, obtained using modern image processing techniques; and to celebrate the same occasion, the Carl Sagan Institute released a video with several noted astronomers reciting Sagan's Pale Blue Dot speech. Watch it HERE.
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References

wikipedia.org/wiki/Pale_Blue_Dot
wikipedia.org/wiki/Carl_Sagan
theatlantic.com/science/archive/2020/02/nasa-pale-blue-dot-voyager/606529
carlsagan.com
NASA Voyager website

Images

1. Pale Blue Dot Revisited, 2020. NASA/JPL-Caltech
2. The Voyager 1 spacecraft. NASA/JPL-Caltech
3. Voyager 1 Flight Path
4. Original Pale Blue Dot photograph. Dot half way up far right band.
5. Carl Sagan. Image Credit: CBS Getty Images
6. Pale Blue Dot book cover, 1994