Sky & Telescope - September 2016 - 2

September 2016
On the cover:

VOL. 132, NO. 3

O B S E RV I N G S E P T E M B E R

Weak gravitational
lensing doesn't alter
distant galaxies' images
as much as is illustrated
here, but the science
gained could be just as
dramatic.

41 In This Section
42 September's Sky at a Glance
43 Binocular Highlight
By Mathew Wedel

45 Northern Hemisphere's Sky
By Fred Schaaf

F E AT U R E S

Astronomy & Big, Big Data

46 Sun, Moon & Planets

How will astronomers cope with the
tsunamis of raw data soon to pour in
from wide-ﬁeld surveys? By Peter Tyson

By Fred Schaaf

48 Celestial Calendar
By Alan MacRobert

Observing Through a
Truly Large Telescope

52 Exploring the Solar System

The author and friends enjoyed a
memorable night of observing through
what was once the world's largest
telescope. By Robert Naeye

54 Deep-Sky Wonders

By Kevin Bailey

By Sue French
S &T T E S T R E P O R T

Find Your Dawes Limit

58 iOptron's iPANO AllView
Pro Camera Mount

The famous resolving-power rule for
telescopes may not apply to you. Try
these close double stars to ﬁnd out.
By Phillip Kane

34
COVER
STORY

By Alan Dyer

Strong Prospects
for Weak Lensing

By Peter Tyson

6 Letters
7 75, 50 & 25 Years Ago

There's more to find online @

SkyandTelescope.com
TIPS FOR BEGINNERS

Here's everything you need to
jump into the fun of astronomy.
SkyandTelescope.com/letsgo

Planetary Processing
with Autostakkert! 2

12 Cosmic Relief
By David Grinspoon

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September 2016 sky & telescope

SKY AT A GLANCE

Our popular column highlights
celestial delights for the upcoming week. Also available as an
app - with sky charts included!
SkyandTelescope.com/ataglance

By Roger W. Sinnott

8 News Notes

This freeware takes the drudgery
out of stacking planetary videos.
By Emil Kraaikamp

ALSO IN THIS ISSUE

4 Spectrum

Astronomers are mapping tiny distortions in the images of distant galaxies
to study the invisible - dark matter
and dark energy. By Govert Schilling

CINDY HUNT / MOUNT WILSON INSTITUTE

44 Planetary Almanac

SPACE ART: CASEY REED

ASTROPHOTO GALLERY

Enjoy readers' best images and
upload your own.
SkyandTelescope.com/gallery

64 New Product Showcase

S&T MARKETPLACE

66 Astronomer's Workbench

Browse personal used equipment and sell your own without
paying a fee.

By Jerry Oltion

73 Gallery
84 Focal Point
By John Mariska

SkyandTelescope.com/marketplace

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Sky & Telescope - September 2016

Table of Contents for the Digital Edition of Sky & Telescope - September 2016