Galactic magnetic fields

 What do we call visible light? We call it color. But the electromagnetic spectrum runs to zero in one direction and infinity in the other, so really, children, mathematically, all of light is invisible —Anthony Doerr, All The Light We Cannot See

Every time I see a magnetic map, I feel like I am privy to something mysterious and elusive: the Earth’s magnetic field. It is something invisible to our naked eyes. Yet we can feel its force. It keeps our feet firmly planted on the ground, instead of hurling our bodies toward the ceiling. It orients birds to their migratory destinations. And lucky for us, it also shields the Earth from billions of tonnes of super-hot charged particles from solar flares— generating beautiful auroras.

Hard to imagine, but the earth sits in an even larger galactic magnetic field, that of the Milky Way’s. This magnetic field permeates through interstellar dust, starlight and gas clouds. If viewed from above, the field would have a spiral shape.

The European Space Agency has released beautiful maps of the Milky Way’s magnetic field using data collected by the Planck satellite. In this relief map, we can trace the structure of the magnetic fields, “viewing” the Milky way from its side or edge.

Here are some zoomed in, colour shaded parts of the above map looking like silky, watery works of art. They are truly magnificient!

Magnetic field near Milky Way’s center and Aquila rift cloud complex . Credit: Planck/ESA

Magnetic field near the Taurus constellation. Credit: Planck/ESA

Magnetic field of the galactic plane (zoomed in). Credit: Planck/ESA