Astronomy – September 2019

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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