Quasars and Pulsars
Years of Discovery: 1963 and 1967
What Is It? The discovery of super-dense, distant objects in space.
Who Discovered It? Allan Rex Sandage (quasar) and Antony Hewish and
Jocelyn Bell (pulsar)
Why Is This One of the 100 Greatest?
Quasars and pulsars represent a new class of objects in space, a new kind of massive,
extraordinarily bright object. Massive, exceedingly dense, and producing powerful radio
and light transmissions, quasars and pulsars radically expanded and altered scientists’ view
of space and space structures.
Quasars are some of the brightest and most distant objects in the universe. Pulsars provide hints of the life path and life expectancy of stars. Their discovery led to a greater understanding of the life and death of stars and opened up new fields of study in astronomy,
super-dense matter, gravitation, and super-strong magnetic fields.
How Was It Discovered?
In the fall of 1960, American astronomer Allan Rex Sandage noticed a series of dim
objects that looked like stars. He cross checked them with a radio telescope to see if they
transmitted radio signals as well as dim light.
Each of these dim objects produced amazingly powerful radio signals. No known object could do that. Maybe they weren’t really stars—at least not stars like other stars.
Sandage called these mystery objects quasi-stellar radio sources. Quasi-stellar quickly
shortened to quasar.
Sandage studied the spectrographic lines of these strange objects (lines that identify
the chemical makeup of a distant star). The lines didn’t match any known chemical elements and could not be identified.
Sandage and Dutch-born American astronomer Maarten Schmidt finally realized that
the spectral lines could be identified as normal and common elements if they were viewed as
spectrograph lines that normally occurred in the ultraviolet range and had been displaced by
a tremendous red shift (Doppler shift) into the visible range. (Doppler shifts are changes in
the frequency of light or sound caused by the motion of an object.)
While that explanation solved one mystery, it introduced another. What could cause
such a giant Doppler shift? In 1963 they decided that the only plausible answer was distance
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