Seeing as the Voyager-1 spacecraft has been in the news recently, here’s the story of a very special photograph that it took 23 years ago known as “The Pale Blue Dot”.
In 1990, 13 years after Voyager-1 left Earth on its mission to visit two of the gas giants and their moons of our solar system, Jupiter and Saturn, one last command was sent to the spacecraft as suggested by Carl Sagan who was then part of the Voyager-1‘s imaging team. That instruction was to turn back around and take one last photo of our solar system before continuing on its epic journey away from the Sun and the planets.
If you look carefully, halfway down the image on the right hand side you’ll notice a tiny point of brightness in the middle of a vertical streak of light. That is Earth, our planet, our home.
In the original photograph transmitted from Voyager-1, NASA stated that Earth was too small for even a single element in its narrow field camera and captured just a crescent measuring a mere 0.16 pixels in length. To achieve “The Pale Blue Dot” image you see above, the picture was enlarged and taken through three colour filters; violet, blue and green, and recombined.
The beam of light that Earth seems prominently placed in is just one of many scattered light rays resulting from taking the image too close to the Sun. The noise and texture in the photograph is a result of the magnification.
We’ve enlarged that photo again just to emphasise how small the Earth is:
Earth being just the size of a pixel, or 4 in the case of this enlargement, sets an interesting premise in astronomy. Although no detail can be made out it still holds great importance, not only for the history of photography, but for humankind.
In one of many videos available on the web, you can hear Carl Sagan talking about his aptly named “Pale Blue Dot” photograph and the significance of it being taken.
Sagan argues that it wasn’t for scientific interest, but instead, it was taken for us.
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.
In fact, there’s more to the Pale Blue Dot than just the single image. It was one of sixty photos Voyager-1 was instructed to take which altogether make up a photo collage known as the “Family Photo” or sometimes referred to as Portrait of the Planets.
In the final image all the planets apart from Mercury and Mars can be seen in their respective positions. Because Voyager-1 was 32 degrees above the ecliptic plane of the solar system it was able to capture our family portrait:
This isn’t the only time Earth has been seen from a great distance. More recently in 2006 the Cassini spacecraft which we’ve covered several times before also took its own version of the Pale Blue Dot. If you look carefully to the left of this beautiful portrait of Saturn you’ll notice a tiny spot of light.
(Yes, this is a real photo!)
That’s not one of Saturn’s moons, that is in fact Earth 930 million miles further in the distance. What makes this also special is that this is only the second photograph of Earth taken from deep space, after Voyager-1’s original photo.
We like how a photo with such little detail can serve so vividly as a reminder to all of us, of our home, who we are, and how insignificant Earth is in this vast expanse of space. To date, Voyager-1’s Pale Blue Dot is the most distant photograph of Earth that has ever been taken and there aren’t any plans in the next 20 years to surpass that record, which might seem a little odd to some of our readers, who may not have even been born when it was taken…
Image credits: Photographs courtesy of NASA.