On July 21, 1974, five years after making history as the first men to set foot on the Moon, Apollo 11 astronauts Michael Collins, Neil Armstrong, and Edwin “Buzz” Aldrin presented the Washington National Cathedral with a small memento from their voyage.

In the four years preceding the Moon rock’s arrival at the cathedral, NASA administrator Dr. Thomas Pain worked closely with St. Louis artist Rodney Winfield to design and construct the window that would house the stone. Known to most as the Space Window, the stained glass creation depicts stars and orbiting planets in hues of blue, green, white, orange, and red, inspired by photos taken from the Apollo 11 mission. Particular care was taken to install the rock, which was placed at the center of a planet (or perhaps a moon?) in the upper half of the window. The sample is encased in a small, air-tight, nitrogen-filled capsule to prevent deterioration. Sealing was conducted in a nitrogen environment to prevent air from entering the capsule during the process.

The rock itself weighs a mere 7.18 grams and is estimated to be around 3.6 billion years old. It was collected from the Moon’s Sea of Tranquility and is composed primarily of basalt, believed to be the result of lava flow. Pyroxferroite, a mineral unknown on Earth, was also found in the sample.

The rock was jointly presented to the National Cathedral by the Apollo 11 crew, the window’s benefactor, Dr. Pain, and Dr. James Fletcher, the presiding NASA administrator at the time. The ceremony commemorated the fifth anniversary of the first lunar landing. President Nixon approved the gift earlier that year.

Though many view science and religion as being at odds with one another, the Space Window at the National Cathedral embodies the intersection of religious thought with the spirit of exploration and the mysteries of the universe. In a September 2012 memorial service held at the National Cathedral in honor of Neil Armstrong, who had died a month prior, Armstrong’s crewmate Michael Collins led the assembly in prayer, saying:

“Creator of the universe, your dominion extends through the immensity of space. Guide and guard those who seek to fathom its mysteries. Especially we thank you this day for your servant Neil Armstrong, who with courage and humility first set foot upon the Moon. Following his example, save us from arrogance, lest we forget that our achievements are grounded in you.”