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SKY & TELESCOPESKY & TELESCOPE

SKY & TELESCOPE March 2019

Since the first issue was published in 1941, Sky & Telescope has become the go-to resource for all things star and space. This magazine is considered the complete resource for the astronomy enthusiast. Offering everything from product reviews, buyer's recommendations, and current events news to tips, how-to articles, and computer software, fascinated readers will find a wealth of information and suggestions on how to hone their hobby. Devoted amateurs, professionals, and academics would all find a subscription to Sky & Telescope magazine of interest.

Country:
United States
Language:
English
Publisher:
F+W Media, Inc. - Magazines
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IN THIS ISSUE

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super stars

WITH THIS ISSUE we kick off a three-part series on famous stars: Polaris, Alpha Centauri, and Betelgeuse. Why did we choose these three over the thousands of others visible to the naked eye? Each holds abiding fascination not only for astronomers, both amateur and professional, but also for a broad swath of the enthusiastic public. Each is iconic in its own way. And each provides a keyhole glimpse into different sectors of cutting-edge science, from the formation of planets to how stars explode. Our first subject, Polaris, easily fits the bill. It’s readily visible to observers in the Northern Hemisphere, even in light-polluted skies. A fixture of star-party outreach, it plays a fundamental role in familiarizing beginners with the constellations. (“See those two stars on the outer edge of the Big Dipper’s…

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animated almanac

I’ve built a device I call the SkyClock that animates S&T’s Skygazer’s Almanac by pointing to sky events identified on the Almanac in real time. The Almanac is mounted on a vertical cylinder that rotates once a day, driven by a stepper motor. A vertical screw connected to the cylinder with friction plates moves a pointer downward one day on the date scale per revolution of the cylinder. Thus, in one year the pointer moves down the Almanac from top to bottom. It uses an inexpensive 5-volt stepper motor driven by a circuit board programmed with appropriate time delays between steps. The link between the rotating cylinder and the screw that moves the pointer downward consists of two spring-loaded plywood disks that supply a constant contact pressure. The ratio of their diameters…

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75, 50 & 25 years ago

March 1944 Titan’s Air “Titan [is] the principal satellite of Saturn. . . . Late in January, Dr. Gerard P. Kuiper . . . reported from the McDonald Observatory in Texas that he had obtained spectra of Titan in red and infrared light. These spectra reveal an atmosphere rich in hydrogen. It is much like the atmosphere of Saturn itself, containing methane (marsh gas) and possibly ammonia. . . . Life, as we know it, is as much out of the question on Titan as on Saturn.” We now know Titan’s atmosphere is largely nitrogen, but it does have some methane. Dorrit Hoffleit’s final remark also needs a different emphasis. Astrobiologists think Titan could well harbor some exotic form of life. March 1969 Missing Mass “A major discrepancy arises when astronomers try to determine…

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insight lander touches down on mars

AFTER A SEVEN-MONTH JOURNEY of almost 500 million km (300 million miles) followed by just over eight minutes of nail-biting anxiousness by mission controllers, the Mars Insight lander has become NASA’s eighth successful landing on the Red Planet. The lander touched down on November 26th at 2:52 p.m. EST in the Elysium Planitia region of Mars, 600 km (370 miles) north of Gale Crater, the stomping grounds of NASA’s Curiosity rover. As NASA’s first dedicated geophysical mission to Mars, Insight will spend the next two years studying the deep interior of the planet by chronicling “marsquakes,” geologic activity, and heat flow from the core (S&T: Dec. 2018, p. 34). The lander will attempt to address specific questions such as: How similar is the interior of Mars to that of other rocky…

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dwarf galaxy found by amateur

IN AN ERA OF GIANT telescopes, one could be forgiven for thinking there wasn’t much left for an enthusiastic hobbyist to discover. But with patience and the right equipment, even an amateur astronomer can stumble onto an undiscovered galaxy. Beneath the dark skies of Pol-lino National Park in southern Italy, Giuseppe Donatiello had been investigating the Andromeda Galaxy with his home-built telescope. In images acquired late in 2010 and 2013, he noticed an unidentified smudge of light. That smudge turned out to be a dwarf spheroidal galaxy — now dubbed Donatiello I — lurking on the farside of Andromeda. “I literally jumped for joy,” says Donatiello. As far as galaxies go, Donatiello I is a runt. Assuming an estimated distance of about 10 million light-years, it appears to be roughly several thousand…

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chilly super-earth may orbit barnard’s star

IN THE CONSTELLATION OPHIUCHUS lies Barnard’s Star, one of the closest and most well studied red dwarf stars in the galaxy. Now, after more than two decades of searches, astronomers have found signs of an exoplanet hiding in its light. Led by Ignasi Ribas (Institute of Space Sciences, Spain), this latest investigation combines new and archival observations spanning 20 years from seven different facilities across the globe. The data, which record the star’s speed toward and away from Earth, suggest that a planet at least 3.2 times as massive as Earth orbits Barnard’s Star every 233 days at a distance of 0.4 a.u. (60 million km). The team reports their find in the November 15th Nature. The putative planet is a bit farther out from its star than Mercury’s average distance from…

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