For many decades, people have observed jets of hot gas spewing from the centers of some galaxies. There are multiple theories as to how those jets form.

Radio astronomers got together and built a synthetic telescope the size of the Earth in order to be able to take a picture of the gas near the black hole at the center of a nearby galaxy, M87.

When they did, and looked at the polarization of the light, they saw twisting lines, which agreed with the prediction of one of the most-favored theories for how these jets are produced.