Accretion disks also create jets of material flowing out from the center to the disk in opposite directions perpendicular to the disk. This matter is orbiting a magnetic field that stretches out from the central mass to very great distances. We’ll use M87’s jet to illustrate how it works. The jet of material streaming out from the center indicates that the galaxy has an Active Galactic Nucleus (AGN for short). That is, it has a supermassive black hole at its center that is accumulating large amounts of matter from an accretion disk. We’ve known about the jet of plasma shooting from the core of M87 since 1918, when astronomer Heber Curtis saw a ray of light connected to the galaxy center – five thousand light-years long and 2 light-years wide. Several things stand out about this jet: It’s blue, it’s very bright, it consists of chunks or knots, and it terminates in a plume. You may have also noted that there is no counter jet going out the other way. The jet is understood to have been formed in a strong magnetic field created by the interactions between the spinning black hole and the rotating accretion disk. Then, at the point where matter from the accretion disk is crossing the event horizon into the black hole, a small percentage of the charged particles are swept into this magnetic field and ejected into the jet at the black hole’s escape velocity, which is near the speed of light for objects as massive as a black hole.