In 1977, two spacecraft launched to the edges of the solar system. Their mission was to explore the outer planets and send information to the team back on Earth. Voyager 1 and Voyager 2 each had different trajectories planned, which meant they would each see different things along their journeys. Voyager 1’s mission was to fly by Jupiter and Saturn. While there, it discovered new moons, even ones covered in volcanoes (we see you Io). Voyager 2 had a bit more to do; not only would it also visit Jupiter and Saturn, it would become the first spacecraft to fly by Uranus and Neptune. In 2012 Voyager 1 left the heliopause—the region of space where the wind from our sun stops having influence on the environment, aka the entry into interstellar space. And recently, like all siblings trying to keep up, Voyager 2 left it too.
Currently both spacecraft are headed in different directions in relation to our sun. If you think of the plane of our solar system as a flat piece of paper, Voyager 1 headed slightly north while Voyager 2 headed south. Part of the reason for this decision was trying to understand the shape of our solar system and to understand exactly where the heliopause might be in either direction. After traveling for over 40 years, Voyager 1 is now almost 14 billion miles from Earth, while Voyager 2 is nearly 12 billion miles from Earth. They are headed in the direction of other star systems, but even traveling at nearly 40,000 miles per hour, it will take Voyager 1 more than 200,000 years to reach the nearest star. Believe it or not, both spacecraft phone into Earth almost every day to send back data from the depths of deep space. In honor of these intrepid explorers, we are going to travel along with both missions this week to gaze upon the outer planets, and then take a look back at Earth as well.
Grab your space suit, we’re headed out to the farthest reaches of our solar system.
On March 24, 1979, Voyager 1 took this photo of Jupiter. Voyager 1’s encounter with Jupiter began in early March and ended in early April, and during that time took a total of 19,000 images and other scientific measurements. Just a few weeks after Voyager 1 departed for Saturn, Voyager 2 showed up to finish the job. One of the most surprising discoveries from the Jupiter encounters were the active volcanoes on the small moon Io. It was and still is the only planetary body apart from Earth with known active volcanoes.Photograph: NASA/JPL
After traveling about 400 million miles, Voyager 2 arrived at Saturn, where it snapped this seemingly sideways photo of the ringed beauty. While the Voyagers were near Saturn they discovered that the winds around the equator move very fast—up to 1,100 miles an hour.Photograph: NASA/JPL
Next stop on the tour takes us much farther out to Uranus. While we can’t see them in this image, Uranus also has a thin band of rings. When Voyager 2 visited the planet in 1986, it discovered 10 new moons, which all got named after characters in Shakespeare plays. Not only did Voyager 2 detect winds of 450 miles per hour in Uranus’ upper atmosphere, it also found evidence of a boiling ocean of water nearly 500 miles below the upper clouds.Photograph: NASA/JPL-Caltech
The final destination on this grand tour is Neptune. On August 25, 1989, Voyager 2 flew over the cloud tops of the planet after traveling nearly 4.3 billion miles to get there. During the encounter it discovered six new moons and found a few oval shaped storms. The spacecraft also found that there was an abundance of hydrogen in the atmosphere, though methane is what gives Neptune its blue appearance.Photograph: NASA/JPL
After Voyager 2 flew past Neptune, NASA officially changed the mission name to the Voyager Interstellar Mission. Both spacecraft were on a trajectory to depart the solar system, but before turning off the cameras, Voyager 1 was commanded to turn and face the Earth. On February 14, 1990, from a distance of 3.7 billion miles, Voyager 1 took this photo now known as the Pale Blue Dot. That’s us, suspended in a sunbeam.Photograph: NASA/JPL-Caltech
