218
BRIGHTER
THAN A GALAXY
BUT IT LOOKS
LIKE A STAR
UASARS AND BLACK HOLESQ
B
y the end of the 1950s,
radio astronomy had given
a new way to look to the
sky. In addition to imaging celestial
objects with light, surveys of the
sky could use radio emissions from
space, showing up previously
unseen features. Radio waves were
found to come from the sun, the
stars, and the center of the Milky
Way, but there were also mysterious
invisible radio sources. In 1963,
Maarten Schmidt, a Dutch
astronomer working with the Hale
Telescope at Palomar Observatory,
California, managed to catch a
glimpse of the light from one of
these objects. When he looked at
its redshift, he discovered somethingIN CONTEXT
KEY ASTRONOMER
Maarten Schmidt (1929 –)BEFORE
1935 Karl Jansky develops
the first radio telescope.1937 Radio engineer Grote
Reber makes the first radio
survey of the sky.1955 The Radio Astronomy
Group at Cambridge begins to
map the northern hemisphere
at 159 MHz.AFTER
1967 Jocelyn Bell Burnell, of
the Radio Astronomy Group,
detects the first pulsars.1972 The first physical, rather
than theoretical, candidate for
a black hole is identified in the
Cygnus X-1 system.1998 Andrea Ghez detects
a black hole four million times
as massive as the sun at the
center of the Milky Way.