Astronomy

CONTENTS

4 ASTRONOMY • JULY 2018

20 COVER STORY

Relativity: Right or
wrong?
Einstein’s relativity replaced
Newton’s gravity. Now
observations of black holes
might test the limits of Albert’s
masterpiece. JESSE EMSPAK

32

Party with the Perseids
his meteor shower is the
most famous, and in 2018 it
will again be one of amateur
astronomy’s great social events.
MICHAEL E. BAKICH

36

Sky This Month
he Red Planet’s revival.
MARTIN RATCLIFFE AND
ALISTER LING

38

StarDome and

Path of the Planets

RICHARD TALCOTT;

ILLUSTRATIONS BY ROEN KELLY

44

Voyage to the bottom

of an alien sea

he next step in space

exploration may be replacing

rovers with underwater robots.

MICHAEL CARROLL

54

Observe deep-sky gems

in Cygnus

Dazzling double stars, open

clusters, nebulae, and even

a galaxy will highlight your

summer of viewing the night

sky. STEPHEN JAMES O’MEARA

60

We test Sigma’s

20mm lens

his wide-angle lens will let

you produce high-quality shots

with just a camera and tripod.

JONATHAN TALBOT

68

Ask Astro

Big stars.

COLUMNS

Strange Universe 12

BOB BERMAN

For Your Consideration 16

JEFF HESTER

Observing Basics 18

GLENN CHAPLE

Secret Sky 64

STEPHEN JAMES O’MEARA

Binocular Universe 66

PHIL HARRINGTON

QUANTUM GRAVITY

Snapshot 9

Astro News 10

IN EVERY ISSUE

From the Editor 6

Astro Letters 8

New Products 62

Advertiser Index 67

Reader Gallery 70

Breakthrough 74

FEATURES

JULY 2018

VOL. 46, NO. 7

32

54

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

is published monthly by Kalmbach Media

Co., 21027 Crossroads Circle, P. O. Box 1612,

Waukesha, WI 53187–1612. Periodicals post-

age paid at Waukesha, WI, and additional

offices. POSTMASTER: Send address changes to

Astronomy, P.O. Box 62320, Tampa, Fla. 33662-2320.

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Go to http://www.Astronomy.com

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ASTRONOMY

: ROEN KELLY

ON THE COVER

Decades of simulations suggest

this is what gas and dust look like

spiraling around a black hole. We

could soon see the real thing.

News

The latest

updates from

the science and

the hobby.

Ask Astro

Archive

Answers to all

your cosmic

questions.

Trips and

To u r s

Travel the world

with the staff of

Astronomy.

My Science

Shop

Perfect gifts for

your favorite

sceince geeks.

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