2019-08-01_Sky_and_Telescope

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SKY & TELESCOPE (ISSN 0037-6604) is published monthly by Sky & Telescope, a division of F+W Media, Inc., 90 Sherman St., Cambridge, MA 02140-3264, USA. Phone: 800-253-

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ONLINE

X-rays reveal swirling

hot gas in the Perseus

galaxy cluster.

ON THE COVER

PHOTO: NASA / CXC / GSFC /

S. A. WALKER ET AL.

FEATURES

Cover Story:

14 Pioneers of the

Invisible Universe

Researchers seeking the X-ray sky

revealed a hot, lively, and revolu-

tionary cosmos. By Monica Young

22 Small-Scope Summer

Embrace the constraints of a small

instrument for deep-sky observing

this season. By Brian Ventrudo

28 Catch a Wind-Blown Bubble

Mysterious in origin and ethereal in

nature, Wolf-Rayet nebulae intrigue

both observer and reader alike.

By Steve Gottlieb

34 Red Dwarf

Habitability Recipe

Life on worlds around the smallest

stars would cope with environments

vastly different from our own.

By Igor Palubski & Aomawa Shields

58 Governing the Planets

This year marks the 400th anniver-

sary of Kepler’s Third Law of

Planetary Motion.

By F. Michael Witkoski

64 Smartphone Nightscaping

The ever-improving quality of

cameras in smart devices makes

nightscape astrophotography a snap.

By Jeff Dai

S&T TEST REPORT

68 Nikon’s Mirrorless Z

By Alan Dyer

COLUMNS / DEPARTMENTS

4 Spectrum

By Peter Tyson

6 From Our Readers

7 75, 50 & 25 Years Ago

By Roger W. Sinnott

8 News Notes

74 Astronomer’s Workbench

By Jerry Oltion

76 Gallery

83 Event Calendar

84 Focal Point

By Dennis Kelly

OBSERVING

41 August’s Sky at a Glance

42 Lunar Almanac & Sky Chart

43 Binocular Highlight

By Mathew Wedel

44 Planetary Almanac

45 Under the Stars

By Fred Schaaf

46 Sun, Moon & Planets

By Fred Schaaf

48 Celestial Calendar

By S. N. Johnson-Roehr

52 Exploring the Moon

By Charles A. Wood

54 Deep-Sky Wonders

By Sue French

THE ESSENTIAL GUIDE TO ASTRONOMY

CONTENTS

2 AUGUST 2019 • SKY & TELESCOPE

August 2019 VOL. 138, NO. 2

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