Astronomy

32 ASTRONOMY • MAY 2018

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

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

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

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

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

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