Bombshell breakthroughs
DISCOVERY OF
URANUS. On
March 13, 1781,
William Herschel
was searching
for binary
stars when he
unintentionally
discovered
Uranus. He
originally
mistook the plan-
et for a comet.
NASA/JPL-CALTECH
VOLCANOES ON IO. Engineer Linda Morabito inadvertently discovered Io’s volcano
Pele in an optical navigation image taken by Voyager 1. Following Pele’s discovery,
hundreds of smaller volcanoes were detected on Io over the years. NASA/JPL/UNIVERSITY OF ARIZONA
X-RAYS AT THE CENTER OF THE MILKY WAY. While attempting to improve long-distance
telephone calls, physicist Karl Jansky accidentally discovered that the center of the Milky Way
is bursting with X-ray light (magenta). NASA/JPL-CALTECH
problem is finding the things you don’t
expect, which hide among the things you
can recognize and the noise in the data.”
Background and instrumental noise,
as Penzias and Wilson know all too well,
can be hard to quantify. As telescopes
and instruments become increasingly
complex, it becomes harder to under-
stand the signatures they leave in the
data. But being able to distinguish
between noise and small, unexpected sig-
nals is key in the search for the unknown.
To tease out the unexpected discover-
ies, Norris is helping develop a project
known as the Widefield ouTlier Finder,
or WTF. With the specific goal of aiding
in unexpected discoveries, WTF will use
complex algorithms and cloud computing
to pull out unusual signals in the data
and reduce the huge quantities of data to
manageable amounts.
Seek and you will find
If you can’t find somewhere new to look,
you can try looking harder than anyone
else. This method paid off for astronomer
Jocelyn Bell. While a graduate student
at the University of Cambridge, Bell was
charged with studying data from quasars
— distant active galaxies — coming from
a radio telescope. Amid all the signals,
she noticed a source that varied too fast
to be a quasar. She had discovered a new
type of star: pulsars.
This technique is the basis of surveys
like the Large Synoptic Survey Telescope
(LSST), which will survey the entire sky
every few nights from its location in
north-central Chile.
“There are some quantifiable reasons
why everyone believes LSST to be a major
revolution for very rare objects and
events,” says Željko Ivezić, project scien-
tist of LSST and professor of astronomy
at the University of Washington in
Seattle. “The volume, the high dimen-
sionality of measurements, and the mea-
surement precision all bode well for
unexpected discoveries and discoveries of
rare objects and events.”
Set to begin watching the night sky in
2021, LSST will provide continual sur-
veillance of the heavens in an exhaustive
manner. With a wide field of view the
GAMMA-RAY BURSTS. In the 1960s, a U.S.
spy satellite was searching for violations of the
Nuclear Test Ban Treaty when it unexpectedly
detected gamma rays coming from the sky
instead of the ground. This was the first evidence
for gamma-ray bursts, which are some of the
most powerful explosions in the universe. ESO
size of 40 Full Moons, LSST will take
images at multiple wavelengths ranging
from visible to near-infrared. Every clear
night, it will log as much as 30 terabytes
of data. Over its 10-year expected life-
time, LSST plans on imaging each section
of the sky a thousand times, creating
more than 30 trillion observations of
40 billion celestial objects.
This style of observation will naturally
single out objects that change in bright-
ness, such as pulsars, supernovae, and
distant quasars, as well as moving objects,
like asteroids and other small bodies in
our solar system. The scientists hope it
may also help identify new variable activ-
ity in the night sky.
Large-scale surveys have been carried
out before, but never to the extent that
LSST will go. Previously, the most exten-
sive survey was the Sloan Digital Sky
Survey (SDSS), which imaged only a
quarter of the sky. LSST will use a tele-
scope nearly three times larger, providing
twice the resolution across a wider range
of wavelengths of light, and it will view a
greater portion of the cosmos.
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