In 19 such sources were found as very distant astronomical radio sources, such as radio galaxies and quasars, and were called superluminal sources. In 1966 Martin Rees pointed out that 'an object moving relativistically in suitable directions may appear to a distant observer to have a transverse velocity much greater than the velocity of light'. His discovery was published in the German journal Astronomische Nachrichten, and received little attention from English-speaking astronomers until many decades later. Superluminal motion was first observed in 1902 by Jacobus Kapteyn in the ejecta of the nova GK Persei, which had exploded in 1901. Perrine studied this phenomenon using photographic, spectroscopic, and polarization techniques.вЂќ Thought to be a nebula, the visual appearance was actually caused by light from the nova event reflected from the surrounding interstellar medium as the light moved outward from the star. telescope (Crossley), he discovered the apparent superluminal motion of the expanding light bubble around Nova Persei (1901). PerrineвЂ™s photograph of November 7th and 8th, 1901, secured with the Crossley Reflector, led to the remarkable discovery that the masses of nebulosity were apparently in motion, with a speed perhaps several hundred times as great as hitherto observed.вЂќ вЂњUsing the 36-in. The apparent superluminal motion in the faint nebula surrounding Nova Persei was first observed in 1901 by Charles Dillon Perrine.

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:ДЄpparent speed = distance to object Г—, the only velocity on the sky that we can measure, is larger than the velocity of light in vacuum, i.e. 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. 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.