In 2017, space no longer feels like the final frontier. But not too long ago, what we knew about the outermost planets in our solar system were more or less educated guesses.
In 1977, NASA launched robotic space probes Voyager 1 and Voyager 2 to capture images and report back on Earth’s more distant siblings. To this day, they’re still exploring. New PBS program “The Farthest: Voyager in Space,” whose premiere aligns with the 40th anniversary of the Voyager 2 launch, tells the decades-long story of the mission.
“It was big? Um, let’s see, what did we know (before the mission)?” joked Charley Kohlhase, who worked on Voyager mission design and navigation, about the far reaches of our solar system in the film. “We knew they were all gas giants, mostly made up of hydrogen and helium and some methane on the outer planets.”
Scientists knew that Jupiter had moons and a big red spot. They knew that Saturn had rings. But they didn’t know for sure what the planets were made of or what the moons were like. There was a desire to get close to these huge planets.
Today, we all think we have a good grasp on our solar system (or at least the basics). But how much do you really know? Here are some solar system facts that are truly triviamaster-worthy.
1. Voyager 2 used “gravity assist” to get from one planet to the next.
Today, Voyager 1 and Voyager 2 have traveled billions of miles. Voyager 2 was launched first and was meant to perform flybys of Jupiter, Saturn, Uranus and Neptune, the planets on the far side of our solar system’s asteroid belt.
To get Voyager 2 from planet to planet, scientists harnessed the power of the planets themselves in the form of “gravity assist.” For example, when Voyager would begin to fly around Jupiter, the gravitational pull and spin of the planet would help shoot it on to the next one, kind of “like a slingshot,” one scientist explains in the film.
The rare alignment of the planets at the time also helped (that wasn’t an accident—scientists planned the launch because of it). It cut the time it would take for Voyager to make the journey. The special alignment only happens once every 176 years.
2. The Voyager probes held messages about Earth, meant for intelligent life beyond our planet.
Now one of the most beloved scientists of all time, Carl Sagan worked on the Voyager mission. He also studied extraterrestrial life. Outside of his other Voyager duties, he was made responsible for creating a message, stored on a golden record, from Earth to any extraterrestrials who might encounter one of the probes.
The record holds traditional greetings from around the world, music and 100 encoded images of the human experience on Earth, including controversial drawings of the nude male and female body.
Even if you’re not the biggest space nerd, “The Farthest” is worth watching just to find out just what was put on that Golden Record—humankind’s intergalactic legacy. It’s a good reminder of how special Earth is.
3. Neptune’s largest moon was hiding an explosive surprise.
When Voyager 2 launched, scientists had already known about the existence of Triton, Neptune’s largest moon, for more than a century. But when the probe did a flyby of the moon, it spotted something that puzzled scientists—ridges on Triton’s surface that didn’t match up.
By creating a 3-D image of the moon’s surface based on the images captured by Voyager, scientists realized the marks weren’t what they appeared to be. They represented geysers of nitrogen gas and dust shooting up from the surface of the moon, activity the scientists had no idea existed previously.
“The Farthest: Voyager in Space” premieres on PBS on Wednesday, Aug. 23. Check your local station’s schedule for broadcast dates and times. Or stream it online at PBS.org.
Katie Moritz is Rewire’s web editor and a Pisces who enjoys thrift stores, rock concerts and pho. She covered politics for a newspaper in Juneau, Alaska, before driving down to balmy Minnesota to help produce long-standing public affairs show “Almanac” at Twin Cities PBS. Now she works on this here website. Reach her via email at [email protected] Follow her on Twitter @katecmoritz and on Instagram @yepilikeit.