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"Take one last look at your precious human moon. Because it cannot help you now!"

Earth's Moon (often referred to as simply The Moon or Luna) is Earth's only natural satellite, and the setting of the final sequence of Portal 2. It is also the latest known location of Wheatley.


Moon 2

The surface of the Moon seen with the Apollo landing site with Earth in the background.

At some point in the late 1970s or early 1980s, Cave Johnson, CEO of Aperture Science, somehow managed to acquire roughly $70 million worth of Moon rock. Upon grinding up and mixing it into gel, he discovered two things: one being that it made a great portal conductor, and the other being that ground Moon rock was "pure poison." He then put it to use in testing, under the name Conversion Gel.

An undefined amount of time later, when Wheatley had taken over the Enrichment Center and allowed it to fall into serious disrepair, part of the ceiling collapsed from the Central AI Chamber. This allowed the Moon to be viewed through the opening made. Chell took advantage of this, and the Moon's portal conducive properties, and shot a portal at the moon. This caused both herself and Wheatley to be sucked into the near-total vacuum of the Moon's atmosphere. Chell was returned to Earth when GLaDOS, newly restored to power, pulled her back in through the portal. However, Wheatley was left to drift through space indefinitely, along with a corrupt Personality Core.


  • The Earth looks similar to what our Earth looks like today, despite the draining of the world's oceans by the Combine as seen in Half-Life 2. This suggests that either the Combine has been overthrown and/or the oceans were somehow restored. This may not be true, as in the credits the photo of Earth is credited to NASA, indicating that it was not created by the developers, and therefore does not have further-reaching implications.
  • It is unknown how the Moon could be seen from the Central AI Chamber. The end credits show that the Enrichment Center's location is hidden deep underground underneath a shed. However, given the modular and internally mobile nature of the Enrichment Center, it is possible that Wheatley moved the chamber closer to the surface and that GLaDOS moved it back deeper underground while Chell was unconscious.
  • Inhaling Moon dust is in fact deadly to humans, which explains Cave Johnson's fatal condition. Due to the Moon's near lack of atmosphere, the jagged texture of the dust is not worn away as it would be by Earth's natural processes. Breathing it in causes lung conditions similar to anything between hay fever and emphysema, depending on how much exposure there was.
  • According to an interview with Erik Wolpaw in the Portal 2 Official Guide, they were originally going to place signs in old Aperture that read things such as "The moon is not your friend." They were even going to put skeletons on the moon during the ending sequence. This was cut with Wolpaw calling it "A good gag that didn't make it in." This connects with Cave Johnson's recording where he says Aperture Science was called to a congressional hearing on "missing astronauts".
  • Doug Rattmann has an extreme obsession with the Moon, as it is seen in all of his drawings and murals. He also states in Portal: Lab Rat that he would have rather have gone to the Moon than help build GLaDOS. The Moon is often referenced in the game as well, including an image hidden in his final transmission showing a companion cube on the Moon. It is unknown if this is foreshadowing, or the Moon serves a greater purpose.
  • During the Moon sequence, a portal is fired at a point on the Moon which is approx. 275 miles (442 km) from the nearest moon landing site which is Apollo 17; making it impossible for a moon landing site to be seen in-game, unless it is an Aperture owned lunar module, or the history of Moon exploration is different in this world.
  • The time it takes the portal beam to reach the moon from the moment the portal gun is fired is roughly the same time it would take a beam of light to reach the moon. This implies the portal gun doesn't violate the Principle of Locality. This also implies the portal gun either fires mass zero particles, which would travel at the speed of light, or it fires highly relativistic, massive particles, which would travel at nearly the speed of light (provided it works by firing particles that adhere to the Standard Model of particle physics).
  • When Chell falls to the ground when the Stalemate Button is pressed, in 3rd person view only her arms and the Portal Gun are shown.

List of appearances

Preceded by
Central AI Chamber (3)
Portal 2 journey (4) Succeeded by
Central AI Chamber (4)
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