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category_outlined / 科学
AstronomyAstronomy

Astronomy

March 2019

The world's best-selling astronomy magazine offers you the most exciting, visually stunning, and timely coverage of the heavens above. Each monthly issue includes expert science reporting, vivid color photography, complete sky coverage, spot-on observing tips, informative telescope reviews, and much more! All this in a user-friendly style that's perfect for astronomers at any level.

:
United States
言語:
English
出版社:
Kalmbach Publishing Co. - Magazines
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building blocks of the cosmos

The vast majority of the stuff in the universe is invisible — either in the form of dark matter or dark energy. But of the 5 percent of the matter/energy in the cosmos that glows, most of it exists within galaxies.Some 100 billion galaxies exist within the cosmos. Within the past couple of years, much ink has been spilled about a 2 trillion figure — that is true, but it includes galaxies that existed in the past. Over time, since the early universe, galaxies have been drawn together by gravity, merging into fewer numbers in the present-day universe. And thus the smaller number of about 100 billion today.Galaxies are the basic building blocks of stuff we know of — the “cells” of the universe that are inhabited by stars, gas,…

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astro letters

(NASA/STScI)Correction from a Hubble expertThe section titled “Hubble’s astounding legacy” in the August issue was well written, but I have one correction to make. The caption under Hubble’s photo of M100, after the optical fix, implies that the Wide Field and Planetary Camera was removed to make the fix. Actually, the High Speed Photometer was removed and replaced with the Corrective Optics Space Telescope Axial Replacement instrument. This contained the lens needed to correct the view for the rest of the instruments. I was fortunate enough to work on the Hubble project from 1985 to 2002. —Kenneth Pulkkinen, Lanham, MD45th anniversary kudosI very much enjoyed “The 10 biggest things in astronomy” in the August 2018 issue. All 10 are certainly major advances, and it was fun to read about them…

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dust in the wind

Captured with NASA’s Hubble Space Telescope, this image shows the bright glow of IC 63, also called the Ghost Nebula, 550 light-years away in the constellation Cassiopeia. This massive cloud of dust and gas gets its vibrant glow from Gamma Cassiopeiae — a behemoth star about 65,000 times brighter and 19 times more massive than the Sun.As the ghostly nebula fades under the onslaught of the star’s energetic photons, its hydrogen glows with reddish light. The blue light in this stunning image comes not from emission, but from reflection, as the dust within IC 63 scatters and reflects some of Gamma Cas’ incoming light. Because it both emits and reflects light, the Ghost Nebula is classified as an emission and a reflection nebula.The Ghost Nebula isn’t the only region affected…

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massive impact crater discovered beneath greenland ice

Plentiful impact craters litter our solar system. On some worlds, craters remain visible for long periods of time; on Earth, however, tectonic processes and weathering erase craters relatively quickly, making them more difficult to discern from the surrounding landscape.Now, an international team of scientists has discovered a 19-mile-wide (30 kilometers) crater that may belong to the meteorite strike that spurred the Younger Dryas period, which saw Earth’s recovery from an ice age cease as frigid temperatures returned for more than 1,000 years.Beneath the iceThe find, published November 14 in Science Advances, is one of our planet’s 25 largest craters. Danish researchers discovered the rounded depression under Greenland’s Hiawatha Glacier in 2015 while looking at maps made using ice-penetrating radar, largely carried aboard NASA’s Operation IceBridge planes. IceBridge has been charting…

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a frozen planet orbiting barnard’s star is discovered

NEW WORLD. Barnard’s star is the closest single star to Earth. Astronomers now know it hosts a super-Earth, illustrated here, just over three times as massive as our own planet. (ESO/M. KORNMESSER)COLD FEET. Barnard’s star b, whose surface is imagined in this artist’s impression, sits 60 percent closer to its star than Earth to the Sun. But the world doesn’t receive much heat, and any volatiles on its surface would freeze into ice. (ESO/M. KORNMESSER)An international team led by researchers from the Carnegie Institution for Science announced the detection of an exoplanet orbiting Barnard’s star, the closest single star to Earth at just 6 light-years away.According to their paper published November 14 in the journal Nature, the astronomers calculate that the newfound world, dubbed Barnard’s star b, is about 3.2…

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neptune blazes a trail

(ASTRONOMY:ROEN KELLY)SLOW MOTION. The outermost major planet takes nearly 165 years to circle the Sun, so it typically spends a lot of time in each constellation. It has been in Aquarius since 2011 and will stay there until 2022, but its longest stretch comes in Virgo, where it will remain for 20 years early next century. The chart shows the percentage of time Neptune will reside in each constellation from March 2019 until it returns to the same position in December 2183.FAST FACTNeptune’s orbit tilts just enough to the ecliptic that it cuts across two nonzodiacal constellations: Cetus and Orion. ■…

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