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Measuring the Tip of Cosmic Icebergs

Observations from NASA's Cosmic Infrared Background Experiment, or CIBER, have shown a surprising surplus of infrared light filling the spaces between galaxies. How did the CIBER team measure this mysterious light? The CIBER data consist of maps of splashy background infrared light, which represent large-scale fluctuations in brightness. By measuring the brightness of these fluctuations, the scientists can estimate the total amount of light.

To understand this, imagine trying to estimate the volume of ice in a collection of icebergs dotting a sea. You can't see below the surface, but can look out at the tips of the icebergs. The bigger the tip, the more iceberg that lies hidden underneath. By measuring the overall pattern of iceberg tips, you could figure out the total amount of ice. In this cartoon, the person in green would estimate more ice than the person in magenta, simply by seeing that the surface is rougher in their pond.

Image credit: NASA/JPL-Caltech

Page Last Updated: November 5th, 2014
Page Editor: Tony Greicius