improve their chances of discovering the
unexpected. Perhaps the way to remain
on the cutting-edge of astronomy is to
look where no one has looked before.
Leaving no stone
unturned
The 15-meter Holmdel Horn Antenna was built in 1959 at Bell Laboratories in Holmdel,
New Jersey, with the goal of performing pioneering work related to satellite communications.
While attempting to use the antenna for research in 1964, radio astronomers Robert Wilson
and Arno Penzias accidentally made a discovery worthy of the Nobel Prize in Physics. NASA
comet. Engineer Linda Morabito found
volcanoes on Io while fiddling with
image contrast to better see the back-
ground stars behind the jovian moon.
Physicist Karl Jansky stumbled upon
X-rays emanating from the center of the
Milky Way while trying to improve
trans-Atlantic phone calls. A U.S. spy
satellite originally detected gamma-ray
bursts while looking for covert nuclear
bomb explosions in the 1960s. And these
are just a few examples.
While astronomy has progressed
through dogged reconciliation of theory
and observation, it has also greatly ben-
efited from things no one could have
expected at the time. Two decades on,
the Hubble Space Telescope has fulfilled
its key goals, but it has also discovered
proplyds (a type of planet-forming disk
around a young star), unveiled dark
energy, and showed that a seemingly
empty section of the night sky was actu-
ally burgeoning with untold numbers of
galaxies. Nobody expected these discov-
eries when Hubble launched.
With rapid advances in technology,
astronomy is emerging into an era of big
surveys. Ultra-high-resolution imaging
and new collection techniques now allow
for unprecedented amounts of data to be
recorded and stored. Astronomers are
already becoming overwhelmed with
more data than they have time to process.
When scientists barely have the time to
search the data for what they’re looking
for, how can they be expected to catch the
paradigm-shifting details no one could
have imagined?
This new era of big-data astronomy
requires a new way of looking at data,
and astronomers are developing ways to
The cosmic microwave background (CMB) is the first light to travel
throughout the universe, left over from just moments after the Big Bang.
Over time, the light that makes up the CMB lost energy, stretching out its
wavelength toward the microwave and radio spectra. NASA/WMAP SCIENCE TEAM
32
A ST R O N O M Y • MAY 2018
Many unexpected discoveries in astron-
omy were possible simply because of new
technology. Galileo’s telescope allowed for
unprecedented views of the sky, uncov-
ering shocking surprises. Similarly, the
Hubble Space Telescope allowed astrono-
mers to look deeper into the universe
than ever before, revealing unimaginable
phenomena. Now, Ray Norris — an
astronomer at Western Sydney University
and the Commonwealth Scientific
and Industrial Research Organisation
in Australia — will tackle an under-
observed section of the universe with a
new survey using radio waves.
The Evolutionary Map of the Universe
(EMU) survey will use the Australian
Square Kilometre Array Pathfinder to
study radio sources in the night sky. Its
goal is to combine breadth and depth to
seek out fainter sources spread across a
wider field of view than previously
attempted. Currently, 2.5 million radio
sources are known. EMU expects to find
70 million more.
Radio sources are often among the
most energetic and explosive objects in
the sky. Black holes, supernovae, and rap-
idly rotating neutron stars (pulsars) are
all known to emit radio waves. The EMU
survey expects to find many objects in
the early universe — some of known
types and some new — that can tell us
how the first stars and galaxies formed.
And Norris has spent a lot of time think-
ing about how best to make those unex-
pected discoveries.
“As telescopes develop, we’ll be getting
more and more data,” says Norris. “The
This simulated image shows how the sky would have appeared
to the Holmdel antenna, which was used by Penzias and Wilson
in 1965 to accidentally discover the cosmic microwave background.
NASA/WMAP SCIENCE TEAM