Superluminal motion - Wikipedia
In astronomy, superluminal motion is the apparently faster-than-light motion seen in some radio galaxies, BL Lac objects, quasars, blazars and recently also in some galactic sources called microquasars. Bursts of energy moving out along the relativistic jets emitted from these objects can have a proper motion that appears greater than the speed of light. All of these sources are thought to contain a black hole, responsible for the ejection of mass at high velocities. Light echoes can also produce apparent superluminal motion.[1]
Superluminal motion occurs as a special case of a more general phenomenon arising from the difference between the apparent speed of distant objects moving across the sky and their actual speed as measured at the source.[2]
In tracking the movement of such objects across the sky, we can make a naive calculation of their speed by a simple distance divided by time calculation. If the distance of the object from the Earth is known, the angular speed of the object can be measured, and we can naively calculate the speed via:
