[Essay Today] The Pale Blue Dot

Summer of 1977. Four planets?Jupiter, Saturn, Uranus, and Neptune?aligned in a row. It was a rare event and a rare opportunity. On August 20 and September 5 of that year, two probes consecutively left Earth from the Cape Canaveral Air Force Station in Florida, USA. Voyager 2 launched first, followed by Voyager 1. The scientific project by NASA to build and launch space probes for outer solar system research is called the Voyager program. It was the beginning of a journey toward the unknown and the infinite.

The mission of the two probes was a "flyby." Voyager 2 passed Jupiter in July 1979, Saturn in August 1981, Uranus in January 1986, and Neptune in August 1989. Voyager 1 flew by Jupiter in March 1979 and Saturn in November 1980. The probes transmitted countless data and photos about the planets and their moons.

After completing planetary exploration, the two Voyagers continued flying and undertook new missions. Voyager 1 became the first human-made object to leave the solar system and enter interstellar space in August 2012. Interstellar space is the space without stars, located between galaxies and external galaxies.

Voyager 1 overtook Voyager 2 on December 19, 1977. It is now located 22.2 billion kilometers away from Earth. Voyager 2 is only 18.5 billion kilometers away. Even traveling at the speed of light, it takes seventeen hours to reach Voyager 2 from Earth. After Voyager 2 sends observation data to NASA, it takes thirty-four hours for the Earth-based technical team to send instructions back. The two probes, built in different environments from Earth and with old equipment, are gradually reaching the end of their lifespans. Scientists expect the Voyagers' missions to conclude around 2024. Until then, Voyager 1 and 2 remain precious windows through which we on Earth can look beyond the solar system.

There was a moment when the lens of the probe, open toward eternity, suddenly looked back. When Voyager 1 had traveled 6 billion kilometers from Earth, NASA turned its camera to photograph Earth. Astronomer Carl Sagan, who led the imaging team for the Voyager program, spent years persuading his colleagues to take this photo. On this day in 1990, Voyager 1 sent back images of the Sun and six planets: Neptune, Uranus, Saturn, the Sun, Venus, Earth, and Jupiter. Mercury was obscured by sunlight, and Mars could not be photographed due to sunlight reflected into the camera.

This photo, taken by Voyager 1 as it bid farewell to the solar system, is called the "Family Portrait." The Earth in the photo is only 0.12 pixels in size. Sagan was deeply moved by the image of Earth sent by Voyager 1. He wrote the book Pale Blue Dot (1994) inspired by this photo.

"That's here. That's home. That's us. Everyone you love, everyone you know, everyone you have ever heard of, every human being who ever was, lived out their