Sky & Telescope - December 2020 - 28

INTERSTELLAR DUST

by Christopher Crockett

Specks Betwee
When thinking about cosmic wonders, we
often sweep interstellar dust under the rug.
But these humble particles play a huge role
in the universe.

A

A K IR A FUJII

t the mere mention of dust in space, Karl Gordon's
face lights up. "I love talking about interstellar dust,"
he says.
Interstellar dust, a cornucopia of microscopic flecks of
solid debris, doesn't usually grab headlines. It's not as flashy
as a supernova nor as exotic as an alien planet. It doesn't
blaze like a star, nor does it bend the imagination like a
supermassive black hole.
But for Gordon (Space Telescope Science Institute) and
many other astrophysicists, interstellar dust is a fascinating
puzzle, a playground of physics that ties together the cosmos.
"When I started, people were like, 'Ohh, you're going
to have to find something else - I mean, you can't make a
career out of this,'" Gordon recalls. "It turns out, you can!"
Gordon spends much of his time measuring the light
from stars, both in our galaxy and others, not in order to
understand the stars themselves but to learn more about the
stuff between them. To him, "the stars are like a nuisance
parameter," astronomer Julianne Dalcanton (University of
Washington) said of Gordon during her lecture at the January 2019 meeting of the American Astronomical Society. "It's
pretty adorable."
Although dust usually lurks in the background, it's essential for understanding the universe. Despite making up just
a tiny fraction of all matter in the cosmos, dust helps build
stellar nurseries, ferries newly forged elements from one generation of stars to the next, and lays the seeds for newborn
planets. It's also a tool. Astronomers use dust to map the
magnetic architecture of our galaxy, pinpoint the locations
of nearby star-forming regions, and unlock secrets about the
peak of cosmic star formation 10 billion years ago.
Even astronomers who aren't drawn to dust's vibrant life
need to know something about its properties. Nearly every
sightline to any celestial object, within or beyond our galaxy,
runs through dust that interferes with observations. There

28

u THE GREAT RIFT Dusty clouds in the Milky Way block starlight from
reaching Earth, creating the illusion of regions of empty space along our
galaxy's disk.
DECEMBER 2 02 0 * SK Y & TELESCOPE



Sky & Telescope - December 2020

Table of Contents for the Digital Edition of Sky & Telescope - December 2020

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Sky & Telescope - December 2020 - Cover2
Sky & Telescope - December 2020 - 1
Sky & Telescope - December 2020 - Contents
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