Two decades of blazar observations, and the mysteries keep piling up

Narrow jets of luminous matter may be emitted toward Earth from the nuclei of active galaxies billions of light-years away. The galaxy then appears as a point source and is called a blazar. A Polish-German team of scientists has, for the first time, analyzed the activity of one such blazar over an extended period and, instead of finding answers, encountered an ever-increasing number of intriguing questions.