X-ray image of quasar 3C 273. 3C 273 was the first quasar to be identified in the 1960's. It is also the nearest quasar at a distance of some 2100 million light years from Earth. It is receding relative to earth at a velocity of 50,000km per second. It appears to be the brightest known quasar at all wavelengths, from radio waves through gamma radiation. The image was recorded by the Einstein Observatory X-ray astronomy satellite. The scatter of dots across the image is the general background of X-rays in the universe, with the exception of the blue dots at upper left, which is another more distant quasar.