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Polarized Dust Lights Up Milky Way


Our Milky Way galaxy is ablaze with dust in this new all-sky map from Planck, a European Space Agency mission with important NASA contributions. The towers of fiery colors are actually dust in the galaxy and beyond that has been polarized. The data show light of 353 gigahertz or 0.85-millimeter wavelengths, which is longer than what we see with our eyes.

When light reflects off surfaces or particles it can become polarized, which means that its electric fields -- normally oriented in all directions -- line up together in the same direction. Polarized sunglasses reduce glare by blocking polarized light.

Planck has special detectors than can pick up polarized light. Most of it comes from dust within our galaxy, but a very tiny fraction travels to us from the dawn of time, from billions of light-years away. That ancient polarized light holds clues about the birth of our universe, and its explosive period of growth called inflation.

Researchers are sifting through data from Planck and other telescopes in an effort to isolate this faint polarized signal. In particular, they are searching for a "curly" pattern of polarized light called B-modes thought to have originated in the very first moments after our universe was born. One of their biggest challenges is separating these ancient B-modes from those that originated in our Milky Way galaxy. This map helps illustrate the daunting task at hand: our galaxy is teeming with polarized light, masking the feeble signal from billions of years ago.