Map of the Milky Way at 408 MHz. The North Polar Spur is indicated
TheNorth Polar Spur is one of the largest structures in theMilky Way galaxy. A giant plume of bright, polarised emission, it extends into the northern galactic hemisphere, roughly perpendicular to thegalactic plane. It cannot be seen atoptical wavelengths, but is visible throughsynchrotron radiation atradio andxray wavelengths.[1][2][3]
It is thought to be produced byionised gas in a strong magnetic field. Its size, and distance from Earth, are yet to be established.
