To be able to see an object that is this far away, we rely on the object to be a strong source of radiation. For the VLBI measurements, quasars (quasi stellar objects) are used due to their very intense radio wave emissions. A quasar can be described as a black hole, with an accretion disk (where matter is drawn into the gravity field of the black hole). Due to the immense pressure at the center, the quasar emits violent jets of radio waves perpendicular to the accretion disk. These radio jets can protrude several light years in each direction and these are the radiation signatures that we observe with our telescopes.