The cover of the September 2023 issue

September Skies, Vesto Slipher, and N.I.N.A.

In the September 2023 issue of Sky & Telescope, learn about the radio array built with off-the-shelf parts — including some from a baking company. But don’t let its simple design fool you: DSA-2000 will offer a sharp-eyed view of the radio sky. First results are expected in 2027; while you wait, dive into the past. Edwin Hubble discovered the expanding universe 20 years ago, in 1923, but the galaxy data he obtained from fellow astronomer Vesto Slipher was key to his realizations. Read Slipher’s side of the story. Then learn more about one of the key variable stars in Andromeda that was instrumental to Hubble’s discovery. With a big enough telescope, you can see it for yourself! Also in this issue, learn about the open-source software named N.I.N.A., which you can use to guide your astrophotography equipment, and find out how watching stars blink out has helped astronomers map asteroids from across the solar system.


DSA-2000: Mining the Radio Sky

An ambitious observatory is taking shape in the American Southwest.

By Govert Schilling

Vesto Slipher’s Fast Stars and Hotrod Galaxies

How one astronomer’s historic discovery of galactic redshifts helped pave the way for modern cosmology.

By Doughlas MacDougal

Hubble’s Eureka Moment

Edwin Hubble’s 1923 insight upended our understanding of the universe.

By Dave Tosteson

Automation with N.I.N.A.

This powerful software controls your imaging equipment while you enjoy the night sky.

By Ron Breacher

Shadow Chasers

Using backyard telescopes and teamwork, observers can discover details about small objects across the solar system.

By Marc Buie

September Ramble Through the Milky Way

Grab your favorite binoculars and get up close with late-summer targets.

By Mathew Wedel

Beyond the Printed Page:

Finder Chart

Explore this detailed chart of the targets from Mathew Wedel’s “September Ramble Through the Milky Way.”


Visit the International Occultation Timing Association’s website.

Lucy Mission

Assist the Lucy Asteroid Ambassadors study asteroids.


Little Gem Delphinus

The starry Dolphin frolics in the shallows of the Summer Milky Way.

By Fred Schaaf

Hyperactive Comet Hartley

An icy visitor pays a return visit this month to delight telescope users.

By Bob King

Suspense at Saturn II

Do recent observations herald the return of ring spokes?

By Thomas A. Dobbins and William Sheehan

Winging it with Cygnus

The eastern wing of the Swan is feathered with deep-sky delights.

By Ken Hewitt-White

Table of Contents

See what else September’s issue has to offer.


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