In the United States, on the 4th of July, we celebrate the declaration of our independence as a sovereign nation with great pride by proudly displaying our countries’ flag and celebrating with fireworks displays across the country. In 1977, just over 1 year after the United States celebrated the 1976 bicentennial of this declaration, a pair of rockets burst into the sky carrying the Voyager 1 and Voyager 2 space probes along with, as noted in a recent SPACE.com article, our nation’s flag. These missions are on trajectories that have taken them well beyond what we commonly think of as the edge of the Solar System and are racing towards the edge of the heliosphere and will enter true interstellar space. So how far away are these two spacecraft?
The Voyager probes were launched in August (Voyager 2) and September (Voyager 1) of 1977, a good year and a half before this GeekDad was born and around 14 years before this year’s crop of graduating High School seniors were born. Voyager 2 is now over 92 astronomical units, or AU, away from our Sun where 1 AU is the average distance from the Sun to the Earth. Voyager 1, on a different trajectory, is now 114 AU from Sol. These distances mean that, right now, commands sent to Voyager 2 take around twelve and a half hours at the speed of light to reach the spacecraft and the telemetry takes another twelve and a half hours to get back to Earth, for a round trip of just over 25 hours. The round trip for Voyager 1 is over 31 hours!
So given these amazing distances, how far away are these 2 spacecraft really? To give you an idea, I am going to lay it out on an American Football field as a way for readers to take go to a local field and seeing how far away this is for themselves. For readers that may not be familiar with an American Football field, the playing field is 120 yards in total with 100 yards, 91.44 meters, being the distance from goal line to goal line.
Placing the Sun at one goal line and working our way out in the solar system (lining up the planets artificially as if they were all in alignment) we first encounter Mercury half of a yard away, Venus roughly another quarter yard away, and Earth will be around the 1 yard line. Stopping here for a moment, at this scale, the Sun is less than half an inch across and the Earth, our tiny home in the Universe, is 1/250th of an inch across. Finishing out the inner Solar System, we encounter Mars at 1.75 yards from the Sun.
Moving out in the Solar System, we meet mighty Jupiter just shy of the 6 yard line. Next up is Saturn just a hair over the 10 yard line, Uranus at almost 22 yards, and Neptune around the 33 yard line. Next is what many consider the edge of the Solar System, the dwarf planet Pluto. Pluto is a bit of an odd-ball as at its closest approach to the Sun it is actually inside Neptune’s orbit but at the furthest point out it is well beyond Neptune at the 53 yard line on our Solar System Football Field.
So that is all well and good, but how far away are Voyager 1 and Voyager 2 at this scale? Voyager 2 is a full 100 yards away from the Sun at the opposing goal line and Voyager 1 has left the end zone and is 123 yards away from the Sun! Maybe the few millionths of an inch trip to and from your summer vacation won’t seem as long now! For more information on the Voyager probes, be sure to check out JPL’s Voyager website.
If you are celebrating the Independence of the United States today, as you look upon the flags flying and the fireworks bursting in the sky, take a moment to look up and think of those two little flags traveling so deep into space.