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

JO

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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


58

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