Forty years ago, in August and September of 1977, a band of humans launched a pair of robots to explore the solar system and probe the infinite darkness beyond. “3, 2, 1. We have ignition and we have liftoff!” Taking advantage of a rare planetary alignment, the twin Voyager spacecraft raced outward toward Jupiter, then used the giant planet’s gravity to slingshot on to Saturn. At Saturn they parted company. Voyager 1 turned upward, leaving the plane of the planets and heading toward interstellar space. But Voyager 2 kept trekking, spiraling outward on a grand tour of the outer planets, toward distant Uranus and Neptune. At each planetfall, fuzzy dots bloomed into worlds. Every image sent back to Earth was another lesson on nature’s ability to surprise. Voyager saw swirls within swirls in Jupiter’s banded jet streams. Volcanoes spouting sulphur on Jupiter’s moon Io, a tormented world twisted and pulled by gravity. And eggshell-smooth Europa, an icy shell around a hidden ocean. Two years after Jupiter, the Voyagers approached Saturn, jewel of the solar system. Its broad rings dissolved into thousands of grooves, like a phonograph record. Braided, kinked and patrolled by tiny moonlets. Voyager probed the methane skies of Titan. It slid past two-faced Iapetus, with light and dark sides. Giovanni Cassini’s disappearing moon. And Enceladus. Trapped under its crust of ice is another dark ocean, and perhaps living creatures. After Saturn, Voyager 1 turned away from the planets but Voyager 2 sailed on. Voyager found ghostly Uranus tipped on its side, its south pole facing the sun. A blue-green bulls eye with faint rings. Voyager slipped passed methane-blue Neptune, a pacific-looking world bruised with dark, violent hurricanes. Antennas on Earth strained to hear the trickle of data from almost 3 billion miles out. Voyager 2’s last port of call was Triton, Neptune’s biggest moon. A mottled ball of exotic ices, plumed with dark geysers of nitrogen. One final world added to Voyager’s tally. But the Voyager mission was not only to observe. Each spacecraft carried a message. A gold record, with a needle and instructions on how to play it. A time capsule from the 1970s, grooved with the sights and sounds of Earth. “I send greetings on behalf of the people of our planet. We step out of our solar system, into the universe, seeking only peace and friendship, to teach if we are called upon, to be taught if we are fortunate.” Of all the voices ever recorded, of all the photographs ever taken, these few will survive the end of our planet. Scratches on gold, adrift in the void. A time capsule from the 1970s, grooved with the sights and sounds of Earth. Of all the voices ever recorded, of all the photographs ever taken, these few will survive the end of our planet. Scratches on gold, adrift in the void. As Voyager 1 climbed away from the planets, it turned its cameras backward. To snap a family portrait of the worlds it was leaving behind forever. The Earth appears as a bright pixel in a wash of scattered sunlight. A “Pale Blue Dot” in the words of astronomer and cosmic sage, Carl Sagan: “Consider 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 Earth is a very small stage in a vast cosmic arena.” No other spacecraft have gone so far, or explored so many new worlds. In the fullness of galactic time the Voyagers might yet be found, but by then the human race could be long extinct. Long after they have ceased speaking to us, the twins will forever drift among the stars. Mute, but carrying sounds and greetings from home. “Hello from the children of Planet Earth” The last lonely evidence that we too once lived in this starry realm, on an island of ice and rock. As Carl Sagan put it: “A dust mote in a sunbeam.”