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.
However, a glimpse in additional wavelengths reveals enormously rich, detailed structures.
Observations show galactic foreground signals combined with cosmic signals originating way back from the Big Bang.
Leveraging observations across many different wavelengths, Planck scientists identified the cause and source of many galactic foregrounds.
The Milky Way’s gas, dust, stars and more create fascinating, measurable structures.
Subtracting out all the foregrounds yields the cosmic background signal, which possesses tiny temperature imperfections.
But the galactic foreground isn’t useless; it’s a map unto itself.
All background light gets polarized by these foregrounds, enabling the reconstruction of our galaxy’s magnetic field.
Quite surprisingly, neutral hydrogen appears to be aligned with the CMB’s polarization.
However, Planck data of distant galaxies matches well with reconstructed magnetic fields.
Scientists continue to evaluate the successes of our best foreground modeling.
What’s certain is that dust grains correlate with these giant magnetic structures.
The link is through star-formation, which occurs inside these obscured regions.
Extragalactic light is unavoidably affected by our galactic magnetic fields, enabling the construction of these beautiful maps.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.