The discovery of thermal anomalies detected on the exterior of the Great Pyramid of Giza last November indicated to researchers that there may be a series of hidden chambers and passageways there, undiscovered by modern Egyptology. In an attempt to verify the presence of these potential chambers, the researchers turned to other imaging methods, including using a technique developed by researchers at Nagoya University in Japan that used deep-penetrating cosmic rays, where evidence of hidden chambers were found in the Bent Pyramid in Dahshour last December.

The specific area of interest identified by the Scan Pyramids team was behind the limestone chevrons above the exterior entrance to the descending corridor leading into the Great Pyramid. Aside from the previously-recorded thermal anomalies, the question of why so many of the chevrons --a structural feature that supports the ceiling above the passageway -- were used for a portion of the corridor that wouldn't require the double layering that is present there. This oddity suggested that there was more to the structure than previously assumed.

The Nagoya team positioned muon-sensitve plates in strategic areas of the pyramid's entrance to replicate their imaging technique from the Bent Pyramid. Muons are a subatomic particle similar to electrons, produced when cosmic rays strike molecules in the atmosphere. These particles can penetrate deeply into rock before they are absorbed, making them useful for this X-ray-like form of imaging, as muons can penetrate the dense limestone structure of the pyramid to reach the imaging plates.

After a 67-day exposure, the plates each showed an excess of muons coming from the same area, an indication that there was a void present that blocked fewer muons than the surrounding structure. Additionally, a separate scan made of the northeastern edge of the pyramid's exterior shows what may be an additional chamber, located 105 meters (345 feet) above the structure's base. More muography imaging will be concluded sometime this month, and is expected to add to the evidence of the hidden chamber above the passageway.