Suspended in a sunbeam

The story of the Pale Blue Dot

Every single papier-mache model you’ve ever seen of the solar system is wrong. It is in fact way, way off. Primary school children seem to have a hard time capturing the vastness of the galaxy with newspaper and glue, and no wonder. Space is big. Enormous, really. And expanding. It’s actually the distances between the planets that make a scale model so impractical—even adult brains need weird food analogies to make it make sense. If the Earth is a pea, Jupiter is a mango 300 metres away. Neptune would be a three-storey wedding cake whole postcodes to the east. Is that any better, or are you now just hungry? 

The outermost planets of the solar system are the Gas Giants, and they have been a very distant mystery to humankind for hundreds of years. It’s kind of like watching a Taylor Swift concert from the uppermost bleachers of the MCG—we know that she’s there and that something is happening, but it’s hard to really glean the details with the naked eye. 

In the late 1970’s aerospace engineer Gary Flandro (real name) discovered there was going to be a rare convergence of the orbits of Gas Giants. Their colossal orbital paths were going to sync up enough for a spacecraft to use the gravity of one planet to slingshot itself to the next, thereby saving fuel and looking cool on diagrams. This voyage was dubbed the Grand Tour. A rich, romantic idea. An excursion to the very outer reaches of our solar system, to take pictures and check vibes and finally, at long last, empower primary school children around the world to bring some scientific accuracy into their papier-macheing.

Meet the Voyagers

Going to space isn’t cheap. Or easy. After they’d gone to the moon a few times—taken some measurements, brought back a few rocks, played a round of golf—NASA’s once-bottomless wellspring of funding and public goodwill ran dry. The Grand Tour’s grand vision to shoot off multiple highly specialised spacecraft with unique purposes and instruments was going to be expensive, so it got canned. NASA found the cash to launch two jacks-of-all-probes, Voyager 1 and Voyager 2, into the great unknown.

Each of these spacecraft was the size of a modest bathroom. They were equipped with a tremendous arsenal of gadgets, most of which sound like weapons in a sci-fi movie: Hydrazine Thrusters, a Cosmic Ray, Plasma Wave Antenna. There was a UV Spectrometer and two massive cameras. Not to mention a big, bulbous, four-metre wide high-gain satellite dish. Attached to the rear of each of the Voyager probes is a twelve inch Golden Record and accompanying phonograph, loaded up with the ultimate Sounds of Earth playlist—whale songs, babies crying, a friendly (but not, like, entirely menace-free) hello from the President of the United States. 

This litany of doodads and gizmos gave us our first ever up-close images of the Gas Giants. Thanks to the Voyager probes, we now know what Jupiter’s surface looks like. We now know that some of Saturn's rings are actually braided together, like an immense hair plait made of splintered asteroids. We now know that Nepturne has rings and auroras and a monster magnetic sphere. We now know all kinds of things about Uranus. Sorry.

The most important discoveries of the intrepid Voyagers were to do with moons. So far out from the heat of the sun, it had been assumed for hundreds of years that the satellites of the Gas Giants would be cold hunks of dead rock. Lifeless. Loveless. Then here was Voyager 1, beaming back composite images of massive volcanoes on the moons of Jupiter. They were shooting lava hundreds of kilometres in the air! The probes found lakes on Europa. Subsurface rivers of gushing hydrocarbons on Io, liquid methane on Titan. They found moons sheathed in kilometres of smooth, woundless ice. Moons alive with storms and fire.

These discoveries taught us about the conditions that might be conducive to the formation of life—weird, brainless, volcano-based, imperceptibly microscopic kinds of life, maybe, but life all the same.

What have they done for me recently?

50 years on, Voyager 1 and 2 are still trucking. Every decade or so, another system is decommissioned, malfunctions or otherwise runs out of juice. Right now as we speak, Voyager 1’s telemetry is on the fritz—if you think it’s hard connecting to a printer in another room, try fixing an ancient computer on the other side of the solar system. It’s 24 billion kilometres away, moving at 64,000 km/h into the galactic void. The Voyagers have even passed through the ‘heliosheath’, a distant astrosphere full of giant magnetic bubbles, with turbulent subsonic winds, in the outermost reaches of the solar system. They are now beyond the influence of our sun.

The probes will fly deeper and deeper into the great cosmic ocean. A message in a bottle. Free from erosion or decay in the vacuum of space, they’ll fly by stars every few hundred thousand years, Golden Record ready and rearing for any aliens that can operate a phonograph. It is estimated (roughly) (very roughly) that Voyager 1 will crash into a sun in about sextillion (10²⁶) years. Not long to go now. 

Before it went too far into deep space, astronomer and Golden Record composer Carl Sagan asked if one of the probes could turn around and take a picture of the Earth. This was poo-pooed by NASA, who were even less financially liquid than before. Voyager 1’s power supplies were depleted. It had a sextillion year journey ahead of it, and there was a risk that light from the sun would damage the camera beyond repair. Sagan conceded that it was a lot of trouble to go to, that the image would have zero scientific value, that it would take years for the signals to even be sent to the probe. He just thought it would look cool. NASA found that hard to argue with.

The Pale Blue Dot

It’s Valentine’s Day, 1990. Picture a gigantic old camera attached to a golden dish, somewhere beyond the orbit of the very furthest planet from our sun. The 1500mm high-res narrow-angle lens twists mechanically but soundlessly around, captures 60 long exposure frames with different colour filters, beams them back to NASA at the speed of light. Three of these frames are usable. They are superimposed on top of each other.

It might be hard to make out the Pale Blue Dot, since it spans just 0.12 of a pixel. It is a pinprick of light, less than halfway up the right most solar ray, a speck suspended in a shard of refracted orange. 

This is Planet Earth. This is where you live, where you’ll always live. This is the sheerness and complexity of the scale we will never, ever be able to capture in our papier-mache models, but good luck to primary schoolers everywhere.

And where else to end but with Sagan himself. Reflecting on the picture that he advocated for for years, he said:

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.

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. 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.