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The whole dewar, before it was sliced open.

Various views inside the dewar.
Images such as this show tiny temperature differences that reflect the texture of the early Universe. The blue areas, very slightly cooler than the pink, are the regions that gravity caused to evolve into the galaxies and clusters of galaxies we see today.
Because this view of the early Universe is so close to the original Big Bang, scientists are building new devices to get more and more detailed microwave pictures from the period. One group used this device, suspended from an enormous balloon, to capture microwaves well above Earth's distorting atmosphere. Microwave light enters the horn and travels to the sensitive detector in the center of the device. This detector must be cooled almost to absolute zero in order to detect the tiny differences in the temperature of the light across the sky.
[images: MW ripple image, detector suspended beneath the balloon]
captions for photographs:
CAPTION: When more sensitive detectors on COBE made a temperature map of the sky, they revealed tiny variations (shown here as different colors) in the microwave afterglow. NASA/GODDARD SPACE FLIGHT CENTER
CAPTION: Suspended beneath this enormous balloon, the FIRS (Far Infra-Red Survey) detector will ascend to an altitude of more than 140,000 feet to map variations in the microwave light. E. CHENG (NASA/GSFC), K. GANGA (PRINCETON / BERKELEY), S. MEYER (UNIVERSITY OF CHICAGO) AND L. PAGE (PRINCETON)
CAPTION: The detector rides inside a gondola that is suspended about a half mile below the balloon. Microwave light enters the horn and travels to the center of the detector where it heats up a single crystal of silicon. E. CHENG (NASA/GSFC), K. GANGA (PRINCETON / BERKELEY), S. MEYER (UNIVERSITY OF CHICAGO) AND L. PAGE (PRINCETON)
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