[music] 532 nanometers. That's the
wavelength of a bright green color, the color of the ATLAS laser
measuring the elevation of the Earth below. When ATLAS receives the photons back
from Earth, it has to filter out the sunlight that naturally reflects off the Earth,
which would overwhelm the detectors. So ATLAS only lets in
light that is exactly 532 nanometers. Sunlight in that
wavelength range will also set off ATLAS detectors, and so computer
programs are needed to filter out those sunlight photons in the data.
[music]