Tools both advanced and simple are crucial to astronomy. Cassini spent thirteen years imaging and collecting other data at Saturn — see some of the stunning photos. LIGO is so technologically impressive that it can detect a change in length of one part in one thousand billion billion. An amateur's observing log helps hone their own observational skills and can provide important data for cosmological events. Learn about the results of a search for advanced ET, explore the ethics of astrophotography, discover an amateur astronomer's solution to creating the perfect observing stool, and more, in the September 2017 issue of Sky & Telescope.
Worlds of Wonder
With its 13-year stint at Saturn coming to a dramatic end, NASA's Cassini orbiter leaves a legacy of unparalleled beauty and scientific discovery.
By Luke Dones
Three Cosmic Chirps & Counting...
From the first discovery to subsequent finds, gravitational-wave signals from the universe's most exotic objects are transforming physics and astronomy.
By Vicky Kalogera
Keeping Track of the Night
An experienced observer describes the benefits and pleasures of keeping an astrojournal
By Bob King
Searching a Trillion Stars for ET
How I helped shrink the possibility that really advanced aliens are broadcasting far and wide.
By Robert H. Gray
Ethics in Astrophotography
Seeing isn't always believing in the digital age.
By Jerry Lodriguss
Beyond the Printed Page
Mini-Flares Might Threaten Life Around Red Dwarf Stars
A new study of data archived from the Galaxy Evolution Explorer (GALEX) spacecraft is revealing just how hard life might be on exoplanets like those in the TRAPPIST-1 system.
TRAPPIST-1h Is Real
Astronomers have confirmed the existence of the seventh planet around the ultracool dwarf star TRAPPIST-1.
Tabby's Star Dims on Cue
Tabby's star, otherwise known as KIC 8462852, dimmed drastically in brightness, giving astronomers an opportunity to figure out what has been causing this star's weird behavior.
Lunar Librations and Phases of the Moon
Librations and other lunar data for September 2017.
ALSO IN THIS ISSUE
Diamond of Three Rings
A total solar eclipse offers the most spectacular of jewels.
By Fred Schaaf
Help Verify a Giant Ringed Exoplanet
For about 25 days in September, its ring system should cross an easily watched star.
By Alan MacRobert
The Enduring Mystery of Luna 2
Amateur observers claimed to see its impact— but no trace of the crash site has ever been found.
By Thomas A. Dobbins
Point your telescope toward these gems of the late-summer sky.
By Sue French
Table of Contents
See what else September's issue has to offer.