11 Quotes by Timothy Robishaw

This hydrogen gas emits radio waves with a wavelength of 21 centimeters, so they come in at about 1,420 megahertz on the radio dial. We were able to find that there is a magnetic field permeating this gas cloud and that its direction is pointing towards us above the cloud and then flips to pointing away from us on the bottom.

An analogy would be when you're scanning the radio dial and you get the same station separated by a small blank space. The size of the blank space is directly proportional to the strength of the magnetic field at the location in space where the station is being broadcast.