35 Years On: Pale Blue Dot and Our Place in the Universe

Voyager 1 photo taken on February 14, 1990 using VG Imaging Science Subsystem – Narrow Angle. Photo Credit: NASA/JPL-Caltech

A long time ago, in our galaxy, billions of miles far, far away—about 3.7 billion to be precise—the NASA space probe Voyager 1 was accelerating out of our solar system. Before its exit, mission managers turned on the probe’s camera and commanded it to take individual frames of six of the planets, including Earth. So, at 4:48 GMT on February 14, 1990, Voyager 1 snapped a series of photos of our collective galaxy. It wasn’t until a couple months later that the image data finally made its way back to the space center to show what had been captured, one standing out in particular of the Earth looking like a tiny speck of dust suspended in a sunbeam—a photo that would go on to be known as the Pale Blue Dot.  

In the 1970s, NASA wanted to take advantage of a rare planetary alignment that only happens once every 175 years or so in which the outer planets of the solar system congregate on one side of the sun. This cosmic lineup, the “Grand Tour” as it was called, would enable a single spacecraft to do a close-up observation of the outer planets Jupiter, Saturn, Uranus, and Neptune. Essentially, as the spacecraft passed each planet, gravity would bend to increase the ship’s velocity toward the next destination, a term coined “gravity assist.” This meant that a planet as far away as Neptune could be reached in 12 years rather than 30 years.  

An artist’s concept of Voyager in space. Photo Credit: NASA/JPL-Caltech

To make this mission simple, the Jet Propulsion Laboratory in Pasadena, California was approved for an $865 million budget by NASA to create two Voyager spacecrafts that would last as long as possible in outer space. Launched from the Kennedy Space Center in Florida—with Voyager 2 taking off on August 20, 1977 and Voyager 1 on September 5, 1977—each probe took a different trajectory toward their destinations. High-gain—or dish-like—antennas on both were used to communicate through the Deep Space Network (DSN) ground systems in order for NASA to receive and transmit the data, along with a recorder for later transmission should communication get lost. In case of contact with extraterrestrial life—who might somehow understand the mechanics of human technology and language—Voyager 1 and Voyager 2 each contained an e-track memory system, computers, and a copper phonograph LP of images and sounds, later dubbed the Golden Record.  

By December 1980, the two Voyagers had completed their intensive exploration of the planets Jupiter and Saturn, Saturn’s rings, and Saturn’s largest moon Titan. Because of this success, Voyager 2 was able to continue on toward Uranus and Neptune. The information that NASA received from both spacecrafts on these giant outer planets of our solar system, their moons, ring systems, and magnetic fields revolutionized the science of planetary astronomy.

Voyager 1 First-Ever Solar System Family Portrait taken on February 14, 1990. Photo Credit: NASA/Jet Propulsion Laboratory-Caltech

Initially, when Voyager 1 was launched into orbit, there was no plan in place for taking the “family portrait” photos of the planets, let alone one of Earth from the furthest reaches of our solar system. This idea was proposed by Carl Sagan, the late astronomer and planetary scientist, who was a central leader in the U.S. space program. Among his many contributions, including on the design and management of the twin probes, Sagan was a member of the Voyager Imaging Team. In 1981, he conceived of the idea to capture a distant image of Earth, with the sentiment being that this photo would show that our world is a fragile, vulnerable, irreplaceable speck in the cosmos. To him, the concept of seeing a photo of the Earth at a great distance may help human beings to understand that this planet is only a point in an immeasurable universe. Space scientists Candy Hansen and Carolyn Porco developed the commands and calculated the exposure time for this enormous feat.

On February 13, 1990, Voyager 1 warmed up its cameras for three hours and then the family portrait began the following morning. First up was Neptune, followed by Uranus, Saturn, Jupiter, Earth, and Venus. Mars was obscured by scattered sunlight, Mercury was too close to the Sun, and Pluto was too small and far away to be detected. After the cameras finished, they were powered down for good. According to Sagan, the 60 total images taken that comprised this mosaic portrait were each composed of 640,000 individual picture elements—i.e. pixels—that took 5.5 hours apiece traveling at the speed of light to reach Earth, with the transmission completed on May 1, 1990. One of those single pixel dots was our home planet.

For the 30th anniversary in 2020, a revised version of Pale Blue Dot was created that utilized modern image processing software and techniques to update the image. Photo Credit: NASA/JPL-Caltech

The Pale Blue Dot image shows the Earth with scattered light that looks like beams of sunlight. By Sagan’s account, it’s an accident of geometry and optics. The Sun emits radiation equally in all directions so, had the picture been taken earlier or later, there would have been no sunbeams to highlight Earth.

In his 1994 book Pale Blue Dot: A Vision of the Human Future in Space, Sagan wrote his famous musings on our single pixel planet. His words—the most timeless love letter to humanity—feel forever prescient, reminding us that we should be more kind to one another and to preserve our pale blue dot.

Carl Sagan reciting the famous excerpt from his book, Pale Blue Dot: A Vision of the Human Future in Space.

Excerpt from Pale Blue Dot:

From this distant vantage point, the Earth might not seem of any particular interest.

But for us, it’s different. 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 there 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.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.

Go further with Carl Sagan’s 1980 documentary series Cosmos: A Personal Voyage.