Sky and Telescope - April 2018 - 2

CONTENTS

THE ESSENTIAL GUIDE TO ASTRONOMY

April 2018

VOL. 135, NO. 4

FEATURES
Cover Story:

The First Galaxies
Astronomers are traveling backwards
in time to observe our universe's
early history.
By James Geach

22 The Little Galaxies That Can
Star-making dwarf galaxies with
a trace of oxygen provide insight
into the ﬁrst galaxies and even the
Big Bang itself. By Ken Croswell

30 The Snake in Spring

By Steve Gottlieb

OBSERVING
41 April's Sky at a Glance

COLUMNS / DEPARTMENTS
4 Spectrum
By Peter Tyson

42 Lunar Almanac & Sky Chart

36 Halley's Comet &
Maya Kings
Did a spectacular, once-in-amillennium meteor shower prompt
the crowning of a king?
By James Romero

43 Binocular Highlight
By Mathew Wedel

Here's a novel way to make your
camera lens perform like a highquality refractor.
By Richard S. Wright, Jr.

58 Sky-Watcher's Stargate
18-inch Dobsonian

45 Under the Stars

By Fred Schaaf

64 Book Review
By Janine Myszka

48 Celestial Calendar
52

Astronomer's Workbench
By Jerry Oltion

By S. N. Johnson-Roehr

72 Gallery

Exploring the Moon
By Charles A. Wood

Focal Point
By Richard S. Wright, Jr.

By Sue French

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ONLINE

ONLINE STORE
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Sky & Telescope's staff.
shopatsky.com

A DOLF SCH A LLER / STSCI

8 News Notes

46 Sun, Moon & Planets

By Dennis di Cicco

Artist's concept of the
early universe's voracious star formation

By Roger W. Sinnott

54 Deep-Sky Wonders

S&T TEST REPORT

ON THE COVER

7 75, 50 & 25 Years Ago

Planetary Almanac
By Fred Schaaf

66 Aperture Masks for
Camera Lenses

6 From Our Readers

MONTHLY SKY PODCAST
Listen as we guide you through this
month's celestial sights. Available
online and for download.
skyandtelescope.com/podcasts

ASTRO TOURISM
Come with us to explore wonders
both on Earth and in the sky.
skyandtelescope.com/
astronomy-travel/

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
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SLCEOSPCEO P E

M AYA OBSERVATORY: V EN TDUSUD / G E T T Y IM AG ES

Step into the serpent's coils to
explore the Hydra I Galaxy Cluster.

http://www.skyandtelescope.com/astronomy-travel/ http://www.shopatsky.com http://www.skyandtelescope.com/podcasts http://www.skyandtelescope.com

Sky and Telescope - April 2018

Table of Contents for the Digital Edition of Sky and Telescope - April 2018