At this moment, two gold-plated copper records are hurtling through space, speeding beyond our solar system. The Voyager 1 and 2 probes launched in 1977, and they’ve since traveled billions of miles from Earth. They are currently the loneliest human-made objects in the universe—and they may stay that way forever—but they were built to make a connection.

The purpose of NASA’s Voyager mission is to illustrate life on Earth to any intelligent aliens that come across the spacecraft. The records on board contain media selected by a committee chaired by scientist Carl Sagan. If extraterrestrials can use the instructions engraved on the disc's cover to access its contents, they’ll be exposed to animal noises, classical music, and photographs of people from around the world. Here are some pieces of media that were chosen to represent our planet.

1. Beethoven’s Fifth Symphony

Ludwig van Beethoven is one of many classical artists representing the music of Earth on the Voyager record. In addition to his Fifth Symphony, the composer’s String Quartet No. 13, Opus 130, is also included on the track list.

2. Chuck Berry’s “Johnny B. Goode”

Though there are many musical compositions on the Voyager Golden Record, the inclusion of “Johnny B. Goode” stirred controversy. Critics claimed rock n’ roll was too adolescent for a project of such significance. Carl Sagan responded by saying, “There are a lot of adolescents on the planet.”

3. A Mandarin Greeting and Invitation

The Voyager project recorded UN delegates from around the world saying greetings in 54 different languages. Most are straightforward, but the Mandarin message includes an invitation. Translated to English, it says: "Hope everyone's well. We are thinking about you all. Please come here to visit when you have time."

4. Humpback Whale Songs

The greetings section of the record features one language that doesn’t belong to humans. Interspersed between the spoken audio clips are the sounds of singing humpback whales. There’s a reason whales were included with the greetings rather than the other animal noises on the record—it was the committee’s way of acknowledging that humans aren’t the only intelligent life on Earth.

5. The UN Building

The Voyager committee chose the UN Building to represent modern urban architecture. The record includes two images of the New York City skyscraper, both taken at the same angle. One depicts the structure during the day and the other shows it at night.

6. A Traffic Jam

The Voyager record highlights many technological marvels from the time it was made, including a rocket and an airplane. The photo of a traffic jam in Thailand that was included may seem less impressive, but it accurately depicts how we use cars on our planet.

7. A Bulgarian Folk Song

The Voyager committee wanted the record's music to represent a wide range of eras and cultures. One track, titled "Izlel je Delyo Hagdutin," is a traditional folk song from Bulgaria. Sung by Valya Balkanska, it’s about a famous rebel leader from the country’s history. Folk music from Azerbaijan, Georgia, and the Navajo people also made it onto the compilation.

8. Ann Druyan’s Brainwaves

While working on the Voyager committee, Ann Druyan had the idea to record her brainwaves, turn them into audio, and copy them onto the record. She spent an hour hooked up to electrical impulse-measuring systems while thinking various thoughts, including what it’s like to fall in love. She and Sagan—her collaborator on the Voyager record project—had recently gotten engaged.

9. A Map of the Solar System

The Voyager mission is designed to travel far, but it will always hold evidence of where it came from. One of the images on the record shows a picture of our solar system with a map illustrating Earth’s location.

10. People Eating

Some human behaviors are tricky to capture in one image. To show the different ways people consume food and drink, the Voyager committee included a photo of someone licking ice cream, someone else biting into a sandwich, and a third person pouring water into their mouth.

11. A Morse Code Message

Another type of communication represented on the Voyager record is Morse code. The message translates to the Latin saying ad astra per aspera, or “to the stars through hard work.”