The sun sets behind BICEP2 (in the foreground) and the South Pole Telescope (in the background).
The BICEP2 telescope's focal plane consists of 512 superconducting microwave detectors, developed and produced at NASA's Jet Propulsion Laboratory.
The tiny temperature fluctuations of the cosmic microwave background (shown here as color) trace primordial density fluctuations in the early universe that seed the later growth of galaxies.
Gravitational waves from inflation generate a faint but distinctive twisting pattern in the polarization of the cosmic microwave background, known as a 'curl' or B-mode pattern.
Graduate student Justus Brevik tests the BICEP2 readout electronics.