205
emissions from the hydrogen
gas that pervades interstellar
space. This discovery allowed
the spiral structure of our galaxy
tobe mapped for the first time.
In the 1960s, radio astronomers
discovered the new phenomena of
quasars and pulsars. We now know
that “quasi-stellar radio sources”—
or quasars for short—are distant
galaxies, which have at their heart
an immense black hole producing
prodigious amounts of energy.
Pulsars are neutron stars—bizarre
balls of compacted matter—
spinning at high speed. Their
discovery confirmed theoretical
predictions made decades earlier.All windows wide open
By the early 1970s, the first orbiting
observatories were operational, and
exploring the ultraviolet, X-, andgamma rays in the skies. Several
series of satellites had been
launched under programs such
as the Small Astronomy Satellites
(SAS) and Orbiting AstronomicalObservatories (OAO). These included
the 1970 SAS-1 for X-ray astronomy
(named Uhuru, the Swahili word for
freedom, in honor of Kenya, from
where it was launched) and OAO-3
(named Copernicus, for the 500th
anniversary of the astronomer’s
birth in 1473). Infrared astronomy
from orbit took longer to achieve
because the telescope must be kept
very cold, but the first surveys of
the infrared sky were undertaken
from the ground.
All parts of the electromagnetic
spectrum were now open to
investigation and the hunt was
even on for the elusive particles
known as neutrinos. Other worlds
in the solar system had become the
targets for future missions. Within
three decades, new technology had
transformed astronomers’ outlook
on the universe. ■NEW WINDOWS ON THE UNIVERSE
1964
1967
1968
1969
1969
1973
OAO-2, the first successful
orbiting observatory,
is launched by NASA.
It is equipped with
ultraviolet telescopes.The Apollo 11 mission
completes President
Kennedy’s project as
Neil Armstrong sets
foot on the moon.Soviet astrophysicist
Victor Safronov figures out
the mathematics behind the
nebular hypothesis of the
solar system’s formation.At the University of Cambridge,
research student Jocelyn Bell
detects the radio signal from
a pulsar, a rapidly spinning
neutron star.British mathematician
Roger Penrose
describes spacetime
“singularities” at the
heart of black holes.
NASA launches the
Uhuru observatory,
the first X-ray
telescope to be
placed into orbit.It’s highly unlikely there are
two lots of little green men,
on opposite sides of the
universe, both deciding
to signal to a rather
inconspicuous planet Earth.
Jocelyn Bell Burnell