Fifty years ago, in the journal Nature, astronomer Maarten Schmidt published a brief paper noting that a star-like object known as 3C 273 was simply too far away to be a star in the Milky Way. Schmidt, of the California Institute of Technology, concluded on the basis of spectroscopic observations that the object was most likely very distant (some two billion light-years away) and hence very, very bright. Shortly after Schmidt’s 1963 paper, 3C 273 and its ilk would become known as quasars, short for “quasi-stellar” objects.
On the fiftieth anniversary of the unmasking of quasars as distant beacons, their secrets have still yet to be fully unlocked, physicist Robert Antonucci of the University of California, Santa Barbara, notes in the March 14 issue of Nature. (Scientific American is part of Nature Publishing Group.) “Have we made good progress in understanding quasars in five decades?” Antonucci writes. “I do not think so.”
The general picture of quasars is now relatively uncontroversial—giant black holes at the centers of distant galaxies feed on gas and even nearby stars, glowing brightly across the electromagnetic spectrum as a result. These active galactic nuclei (AGNs), as they are known, can also launch jets of high-speed particles, as in the case of quasar 3C 273.
Quasar 3C 273 and its jet, as viewed in x-rays.
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