Evolution of Venus, Extinction of the Dinosaurs, and Gegenshein
In the October 2021 issue of Sky & Telescope, we’re taking a look into some age-old mysteries. Planetary scientists suspect that Venus may have had liquid water oceans in the past. So what happened? We’re also searching for clues to a prehistoric murder case: the extinction of the dinosaurs. We have two suspects: an asteroid strike or volcanic eruptions. But without a smoking gun, scientists can’t agree which is the culprit. Next, we’re hunting down the pieces of the Sagittarius Dwarf Spheroidal Galaxy, one of the many small galaxies that the Milky Way has ripped apart over the eons. And while several sources credit Esprit Pezenas with first noting the Gegenschein in 1730, his account in the Journal de Trévoux leads Don Olson to believe that what Pezenas actually saw was an aurora. So we’re combing through history for the true discoverer of this phenomenon.
Venus: Inevitability or Catastrophe?
Studying Venus can help us understand how large, rocky worlds evolve — and whether the hellish surface conditions on the second planet forebode a similar fate for Earth.
By Paul Byrne
The Case of the Dead Dinosaurs
Scientists can’t agree on whether an asteroid strike or volcanic eruptions caused the downfall of the dinosaurs.
By Shannon Hall
Meet the Neighbors — The Sagittarius Dwarf Spheroidal Family
Our Milky Way has torn a nearby galaxy to shreds. Find out how you can observe its remnants.
By Steve Gottlieb
Who Discovered the Gegenschein?
It’s time to set the record straight and finally give credit where credit is due.
By Donald W. Olson
Sky & Telescope’s June solar-eclipse flight was an event worth losing sleep for.
By Bob King
Astrophotography with remotely operated telescopes is easier than you might think.
By Ted Wolfe
Beyond the Printed Page:
Enjoy this comprehensive survey of sinuous rilles on the Moon.
Remnants of the Sagittarius Dwarf Spheroidal Galaxy
Use these finder charts to locate the objects associated with the Sagittarius Dwarf Spheroidal Galaxy’s remnant core.
Know exactly when an aurora is about to appear with NOAA’s Real Time Solar Wind live feed.
Check out Halton Arp’s Atlas of Peculiar Galaxies.
ALSO IN THIS ISSUE:
This strange zodiacal constellation offers more than first meets the eye.
By Fred Schaaf
October is one of the most rewarding times of the year to monitor the midnight sky.
By Bob King
Understanding the origins of these fine Moon features can enhance your observing experience.
By Charles A. Wood
Setting up your mount correctly is an important first step in creating great astrophotos.
By Tony Puerzer
Table of Contents
See what else October's issue has to offer.
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