Astronomy - USA (2019-09)

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4 ASTRONOMY • SEPTEMBER 2019


22 SPECIAL ISSUE


Are we alone


in the universe?


Mars, Pluto, and an array of


icy moons offer possible places


where microbial life might


have existed — or might yet


exist today. DAVID J. EICHER


24


Is there life on Mars?


Earth’s neighbor once had a


climate conducive to life. Now


scientists are trying to learn if


the Red Planet turned those


chances into reality. JIM BELL


30


How we might find


life on Europa


Jupiter’s icy moon is a great


candidate for habitability.


But life’s best chance to


exist is beneath the crust.


MARA JOHNSON-GROH


36
Sky This Month
Neptune peaks in Aquarius.
MARTIN RATCLIFFE AND
ALISTER LING

38
StarDome and
Path of the Planets
RICHARD TALCOTT;
ILLUSTRATIONS BY ROEN KELLY

44
Searching for life on
Saturn’s big moon
Titan’s soupy skies drizzle
complex hydrocarbons onto
the moon’s surface, potentially
providing the building blocks
of life. MICHAEL CARROLL

50
The enigma of Enceladus
This tiny saturnian moon may
be, pound for pound, the most
valuable piece of real estate in the
solar system. MORGAN L. CABLE
AND LINDA J. SPILKER

56
What lies beneath
Triton’s ice?
Neptune’s moon Triton shows
tantalizing evidence of water
beneath its jumbled crust,
making it a high-priority
target in the search for life.
NOLA TAYLOR REDD

62
Life’s prospects on Pluto
Who would have thought this
dwarf planet could nurture
life? The idea seemed ludicrous
before New Horizons explored
the world. FRANCIS NIMMO

IN EVERY ISSUE


From the Editor 6


Astro Letters 8


Advertiser Index 69


New Products 71


Breakthrough 74


FEATURES


SEPTEMBER 2019
VOL. 47, NO. 9

CONTENTS 24


Astronomy (ISSN 0091-6358, USPS 531-350)
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ONLINE
FAVORITES

9


QUANTUM GRAVITY
Everything you need
to know about the
universe this month:
Hubble’s take on cosmic
expansion, clues about
Mars’ past climate,
tectonic acivity on the
Moon, solar system
worlds from the inside,
and more.

COLUMNS


Strange Universe 14
BOB BERMAN

Binocular Universe 68
PHIL HARRINGTON

Secret Sky 70
STEPHEN JAMES O’MEARA

Observing Basics 72
GLENN CHAPLE

ON THE COVER
Our special report looks at the
prospects for life, past or present,
in the solar system. NASA/JHUAPL/SWRI

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