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. To understand how scientists measured the amount of this mysterious light, imagine using the tips of icebergs to estimate their total volume of ice.

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.

Caltech manages JPL for NASA. The work was supported by NASA, with initial support provided by JPL's Director's Research and Development Fund. Japanese participation in CIBER was supported by the Japan Society for the Promotion of Science and the Ministry of Education, Culture, Sports, Science and Technology.Korean participation in CIBER was supported by the Korean Astronomy and Space Science Institute.

For more information about CIBER, visit http://ciber.caltech.edu/rocket.html.