The dust in the Milky Way, shown in darker and redder colors, are regions where new star formation is taking place. These dusty regions are correlated with the magnetic fields present in our galaxy, and the background light gets polarized in a measurable way as a result. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

This Is What The Milky Way’s Magnetic Field Looks Like

If you thought the Planck satellite just made temperature maps of the cosmic microwave background, this will astound you.

The Milky Way, to human eyes, appears as simply a mix of stars and light-blocking dust.

A map of star density in the Milky Way and surrounding sky, clearly showing the Milky Way, the Large and Small Magellanic Clouds (our two largest satellite galaxies), and if you look more closely, NGC 104 to the left of the SMC, NGC 6205 slightly above and to the left of the galactic core, and NGC 7078 slightly below. In visible light, only starlight and the presence of light-blocking dust is revealed, but other wavelengths have the capacity to reveal fascinating and informative structures far beyond what the optical part of the spectrum can. (ESA/GAIA)

However, a glimpse in additional wavelengths reveals enormously rich, detailed structures.

This ultra-detailed view of the Milky Way spans many different wavelengths of light, and as such it can reveal gas, charged particles, many types of dust, and many other signals that appear in the microwave and millimeter wavelength ranges. The Planck satellite provides us with our best all-sky view of the cosmos in this wavelength range. (ESA/NASA/JPL-CALTECH)

Observations show galactic foreground signals combined with cosmic signals originating way back from the Big Bang.

The Planck satellite constructed all-sky maps of the sky in nine different wavelengths of light, at frequencies spanning from 30 GHz all the way up to 857 GHz: frequencies that can only be observed from space. Although the foreground features in the Milky Way are quite prominent, the main science goal of Planck was to analyze the background light: the cosmic microwave background. (ESA AND THE PLANCK COLLABORATION)

Leveraging observations across many different wavelengths, Planck scientists identified the cause and source of many galactic foregrounds.