Apollo 11 astronauts carried a small silicon disc etched microscopically with goodwill messages from four U.S. presidents—Dwight Eisenhower, John Kennedy, Lyndon Johnson and Richard Nixon. 

“The journey of the astronauts is more than a technical achievement; it is a reaching-out of the human spirit,” the message from Nixon read. “It lifts our sights; it demonstrates that magnificent conceptions can be made real. They inspire us, and at the same time they teach us true humility.”

This disc, about the size of a half-dollar coin, was transported in an aluminum capsule that Neil Armstrong and Aldrin left on the Sea of Tranquillity. It was meant to celebrate the moon landing as a triumph for all of humanity, despite the Cold War tensions between the United States and the Soviet Union that had originally ignited the race to the moon.

As such, the disc carried statements from leaders of 73 countries around the world, many in native languages, that “congratulate the United States and its astronauts and also express hope for peace to all nations of the world,” according to NASA.

A plaque attached to part of the Apollo 11 landing module, which was left on the moon after the astronauts used it as a launch pad for their lift-off, bears a similar inscription: “Here men from the planet Earth first set foot upon the moon, July 1969 A.D. We came in peace for all mankind.”

After Apollo 11 astronauts accomplished their white-knuckled descent to the moon, they set up a collection of scientific instruments, known as the "Early Apollo Scientific Experiment” to remain on the moon’s surface for various tests.

One of the most notable among them is the Laser Ranging Retroreflector. The device, essentially a small array of special mirrors, reflects laser beams sent from observatories on Earth. By measuring the time it takes for these beams to travel to the moon and back, scientists have been able to precisely track the moon’s orbit and determine that it is moving farther away from Earth at a rate of 1.5 inches (3.8 centimeters) per year.

While other science instruments left on the moon fell silent years ago, this experiment is remarkably still operational. Its longevity is largely due to the fact that it doesn’t require any power to operate, according to NASA.

The first picture Neil Armstrong took after landing on the moon shows a jettisoned waste bag—likely with poop inside—one among 96 such bags that Apollo astronauts discarded on the moon across six missions.

There was no bathroom on the Apollo spacecraft, so astronauts relied on a basic system using a plastic bag taped to their buttocks for in-flight fecal collection. The simplicity of it meant spills were inevitable. 

“Give me a napkin, quick,” Apollo 10 astronaut Tom Stafford sounded an emergency six days into the mission, according to a NASA transcript. “There’s a turd floating through the air.”

Because astronauts had to lighten their spacecraft to make room for moon rocks, they ended up discarding 96 bags filled with urine, feces and vomit onto the moon’s surface. 

“Very little has changed,” says Jack Burns of the University of Colorado, Boulder. “Almost everything they left behind, including their waste products, are still preserved on the surface.”

More than 50 years later, that human waste has sparked the interest of astrobiologists. Scientists are eager to investigate whether microbes that flourish in human feces have mutated or survived in a dormant state, which could provide valuable insights into how resilient microbial life can be in the harsh lunar environment—and whether it might be capable of seeding life across the universe.

When Armstrong set foot on the moon on July 20, 1969, he famously said, “That’s one small step for a man, one giant leap for mankind.” 

The boots that made those iconic steps were left behind on the moon, for practical reasons. “They were deliberately trying to lose mass because they were very limited in fuel to get back off the lunar surface,” says Chris Impey, a professor of astronomy at the University of Arizona. “Even going into the missions, they knew they were going to discard a lot of things.”

The bootprints, however, remain intact, as there is no wind or atmosphere on the moon to disturb them. Eventually, the prints will be buried under lunar soil displaced by meteorite impacts in a “very slow process,” says Burns—one that will take at least a few million years. 

For more ceremonial purposes, Apollo 11 astronauts planted a U.S. flag in the moon’s soil. While it was blown over by rocket exhaust when they left, each subsequent moon landing mission continued the tradition. These flags do not represent territorial claims on the moon but are merely symbolic gestures, according to NASA.

Humanity's exploration of the moon is not just a tale of scientific achievement but also one of personal stories and sacrifices. Commemorating some of them is a tiny, 3.5-inch abstract aluminum sculpture named the “Fallen Astronaut,” which was created by Belgian artist Paul Van Hoeydonck and placed—without publicity—on the moon by Apollo 15 astronauts in 1971. 

Scott left it alongside a plaque memorializing eight American astronauts and six Soviet cosmonauts killed during previous missions. The Fallen Astronaut is often referred to as the first art installation on the moon.

In similar spirit, the Apollo 11 crew had left two Soviet medals on the moon to honor the late Russian cosmonauts Yuri Gagarin and Vladimir Komarov.

Another personal memento left on the moon was a 3-by-5-inch plastic-encased photo of Apollo 16 astronaut Charles Duke, his wife Dorothy, and their sons Charles and Thomas taken on Earth and left on the moon in 1972.

The message on the back reads: "This is the family of astronaut Charlie Duke from planet Earth who landed on the moon on April 20, 1972."

Duke left the photo in the Descartes Highlands, which was the Apollo 16 landing site. Over 50 years of wild temperature swings in the region mean it has likely faded by now.

Late American geologist Eugene Shoemaker, who pioneered the field of astrogeology and is best known for co-discovering the Comet Shoemaker-Levy 9, is the only person to date whose ashes have been buried on the moon.

Shoemaker was set to be the first geologist on the moon, but a medical problem disqualified him. Instead, he spearheaded the effort to make science an essential element of the Apollo program. That included turning astronauts into scientists through field trips to Meteor Crater in Arizona, where he provided them with hands-on experience in identifying and collecting geological samples. 

After his passing in 1997 in a car crash while crater-hunting in Australia, a portion of his ashes was carried aboard NASA's Lunar Prospector spacecraft. The probe crashed near the moon’s south pole two years later.

Twelve American astronauts have walked on the moon, but Apollo 14 commander Alan Shepard holds the unique distinction of being the only one to have played golf there.

Shepard famously brought a custom 6-iron head and two golf balls to the moon. After completing the scheduled tasks on the lunar surface, he attached his makeshift club to a tool designed for scooping lunar rock samples. His bulky suit was so stiff that he had to use only one-armed swings, and he shanked his first ball into a nearby crater. The second sailed “miles and miles and miles” in the moon's one-sixth gravity, Shepard declared in front of a TV camera. 

He didn’t mean that literally, of course. He estimated the ball traveled about 200 yards (600 feet). Ball-tracking technology wasn’t available at the time; however, 50 years later, analysts who studied images from NASA’s Lunar Reconnaissance Orbiter concluded that Shepard’s golf ball drifted a more modest 40 yards (120 feet).

NASA had allowed Shepard to carry out the "moon shot" only as long as it was a non-commercial activity, which is why the brand of the golf balls remains unknown to this day.