What is causing a huge jet to be ejected from the heart of galaxy M87? The galaxy is the yellow blob at the top left of the picture.

The most likely theory is that the jet originates in a disk of superheated gas swirling around a black hole at the galaxy centre. Calculations show that the result of such an arrangement would be this jet of electrons and other sub-atomic particles ejected outward at just below the speed of light, emitting eerie blue light which contrasts with the yellow glow of the billions of unseen stars in the galaxy

The jet length is 5,000 light years i.e. 30 thousand million miles (between the arrows). Note that at radio wavelengths the jet can be traced out to 100,000 light years.

M87 is a giant elliptical galaxy (i.e no spiral structure) 50 million light years from Earth.

Hubble photo, taken February 1998.

Photo Credit: J.A Biretta et al.,Hubble Heritage Team (STScI/AURA),NASA