[7] Given its distance from Earth and visual magnitude, 3C 273 is the most distant celestial object average amateur astronomers are likely to see through their telescopes.

This is the optically brightest quasar in the sky from Earth with an apparent visual magnitude of ~12.9, and one of the closest with a redshift, z, of 0.158.

[5] It is one of the most luminous quasars known, with an absolute magnitude of −26.7,[9] meaning that if it were only as distant as Pollux (~10 parsecs) it would appear nearly as bright in the sky as the Sun.

Polarization with coincident orientation has been observed with radio, infrared, and optical light being emitted from a large-scale jet; these emissions are therefore almost certainly synchrotron in nature.

[12][13] This is a prototype of an Active Galactic Nucleus, demonstrating that the energy is being produced through accretion by a supermassive black hole (SMBH).

In 1995, optical imaging of the jet using the Hubble Space Telescope revealed a structured morphology evidenced by repeated bright knots interlaced by areas of weak emission.

In 1963, Maarten Schmidt[8] and Bev Oke[20] published a pair of papers in Nature reporting that 3C 273 has a substantial redshift of 0.158, placing it several billion light-years away.

Also, many active galaxies had been misidentified as variable stars, including the famous BL Lac, W Com and AU CVn.