Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2015 January 27
Our Galaxy's Magnetic Field from Planck
Image Credit & Copyright: ESA/Planck; Acknowledgement: M.-A. Miville-Deschênes, CNRS – IAS, U. Paris-XI
Explanation: What does the magnetic field of our Galaxy look like? It has long been known that a modest magnetic field pervades our
Milky Way Galaxy because it is seen to align small
dust grains that
scatter background light. Only recently, however, has the
Sun-orbiting Planck satellite
made a high-resolution map of this field. Color coded, the
30-degree wide map confirms, among other things, that the
Galaxy's interstellar magnetism is strongest in the central disk. The rotation of charged gas around the
Galactic center creates this magnetism, and it is hypothesized that viewed from the top, the
Milky Way's magnetic field would appear as a spiral swirling out from the center. What caused many of the details in this and
similar Planck maps -- and how magnetism in general affected our
Galaxy's evolution -- will likely remain topics of research for years to come.
Tomorrow's picture: joy to the sky
