2019-06-01+Sky+and+Telescope

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INTERACTIVE SKY CHART

Find out what the sky looks like for

your time and place. You can also

print the chart as a handout.

skyandtelescope.com/

interactive-sky-chart

MONTHLY SKY PODCAST

Listen as we guide you through this

month’s celestial sights. Great for

those learning how to navigate the

night sky!

skyandtelescope.com/podcasts

BEGINNERS’ GUIDE

Print out our free, 10-page handout

to give out at star parties and other

community events.

skyandtelescope.com/

getting-started

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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-

0245 (customer service/subscriptions), 617-864-7360 (all other calls). Fax: 617-864-6117. Website: skyandtelescope.com. Store website: shopatsky.com. ©2019 F+W Media, Inc.

All rights reserved. Periodicals postage paid at Boston, Massachusetts, and at additional mailing offi ces. Canada Post Publications Mail sales agreement #40029823. Canadian return

address: 2744 Edna St., Windsor, ON, Canada N8Y 1V2. Canadian GST Reg. #R128921855. POSTMASTER: Send address changes to Sky & Telescope, PO Box 420235, Palm Coast, FL

32142-0235. Printed in the USA.

ONLINE

Artist’s concept evok-

ing the expanding

universe we inhabit.

ON THE COVER

NICOLLE R. FULLER, SAYO-ART LLC

FEATURES

14 Lighting a Cosmic Fuse

“Standard candle” Type Ia super-

novae are not as uniform as

astronomers once thought they

were. By Shannon Hall

Cover Story:

22 Constant Controversy

Astronomers and cosmologists can’t

agree on the current expansion rate

of the universe. By Govert Schilling

30 Hunting Elusive Prey

Face-on spiral galaxies are among

the most graceful objects to behold.

By Ted Forte

36 The Dawes Limit

and Beyond

The author fi nds that two of his

telescopes have lower limits than

what theory predicts.

By Don Ferguson

58 Seeing Stars in Glacier

The fi rst cross-border International

Dark Sky Park offers everything

you need for a fulfi lling night under

the stars. By Amy Grisak

64 The Quest for Round Stars

Great deep-sky imaging begins with

well-tracked exposures.

By Ron Brecher

S&T TEST REPORT

70 Meade’s Deep Sky Imager IV

By Dennis di Cicco

COLUMNS / DEPARTMENTS

4 Spectrum

By Peter Tyson

8 From Our Readers

9 75, 50 & 25 Years Ago

By Roger W. Sinnott

10 News Notes

57 Book Review

By S. N. Johnson-Roehr

74 Astronomer’s Workbench

By Jerry Oltion

76 Gallery

84 Focal Point

By Robert Vanderbei

OBSERVING

41 June’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 Solar System

By Thomas A. Dobbins

54 Deep-Sky Wonders

By Sue French

THE ESSENTIAL GUIDE TO ASTRONOMY

CONTENTS

2 JUNE 2019 • SKY & TELESCOPE

June 2019 VOL. 137, NO. 6

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