Cosmic Pursuits

Basic astronomy and night sky information

Recent Astronomy Articles at Cosmic Pursuits

The Wonderful Star

By Filed Under: Stargazing

The red giant star Mira A, a highly evolved variable red giant star, and Mira B a small but dense white dwarf. Image at left was created with data from NASA’s Chandra X-Ray Observatory. The image at right is an artist’s conception of this interacting star system. Credit: X-ray image courtesy NASA/CXC/SAO/M. Karovska et al.; Illustration: CXC/M.Weiss.

As a reader of Cosmic Pursuits, you no doubt believe that all stars are wonderful. But one star, it turns out, is more wonderful than most. The star Mira, or Omicron Ceti, in the constellation Cetus, has been known since ancient times, but its nature began to emerge in the 16th century when a German pastor and amateur astronomer discovered the star’s brightness changed periodically, by a huge amount, every eleven months. And it was but the first discovered of many such stars. [Read more…] about The Wonderful Star

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The Greatest Astrophoto in History (So Far)

By Filed Under: History and Famous Astronomers

Fifty years ago this December, at the end of a ghastly year of assassinations, riots, war, and political unrest, three astronauts became the first humans to leave the gravitational embrace of Earth, orbit another world, and return safely back home. Apollo 8 was a mission of astonishing audacity, put together in great haste to counter a possible Soviet lunar mission which U.S. intelligence sources believed was imminent. And it served as a major step to fulfill President Kennedy’s promise to land a man on the Moon and return him safely to Earth by the end of the 1960s [Read more…] about The Greatest Astrophoto in History (So Far)

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Algol, the “Demon Star”

By Filed Under: Science

An artist’s conception of an eclipsing binary star.

Algol, the second brightest star in the northern constellation Perseus, is the finest example of an eclipsing variable star in the entire sky. In this compact stellar system, two stars revolve around their common center of mass in a rhythmic and precise gravitational dance, and the resulting eclipse causes the brightness of the star to vary like clockwork to a degree that’s easily perceptible to the human eye. And you can watch it from your backyard. No telescope required [Read more…] about Algol, the “Demon Star”

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A Visit to Mount Wilson Observatory

By Filed Under: History and Famous Astronomers

The dome of the 100″ Hooker telescope at Mt. Wilson Observatory and tour guide Nik Arkimovich. Image credit: Joe Bergeron.

One hundred years ago, the universe was quite small, or at least people thought it was. Not so small that you could put it in your pocket, but limited to the Milky Way Galaxy only, which was thought to be about 30,000 light-years across, or maybe a little more.

Beyond that, if there was anything at all, it was simply an empty void.

That’s because no one was sure what the so-called “spiral nebulae” really were. They were dotted across the sky, often in clusters, though they were scarce along the band of the Milky Way. When astrophysicists analyzed their light spectroscopically, those spectra showed star-like characteristics, but no telescope on Earth could reveal individual stars, either visually or photographically. They remained mysterious, and often beautiful, whirlpools of light.

So although some astronomers suspected these spirals were in fact remote “island universes”, more of them believed they were closer, lesser things, perhaps infant solar systems in the process of forming.

Slightly less than one hundred years ago, these questions were resolved, along with the galaxies themselves, and the size of the known universe expanded one hundred thousand times or more, almost overnight.

And that’s where the Mount Wilson Observatory in California comes in. Its namesake mountain sits at the edge of the vast carpet of artificial lights known as the Los Angeles Basin, looking down on it from 5700 feet above the not-so-distant Pacific Ocean. Today that massive light pollution renders the observatory useless for most kinds of nighttime astronomical research. In its heyday in the early 20th Century, it was the world’s greatest center of astronomical discovery. It was one of the first observatories ever to be sited on a mountaintop for performance, not in or near a city for convenience. Back then it could ignore the feeble lights of Los Angeles and the other small communities flickering below [Read more…] about A Visit to Mount Wilson Observatory

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Dawn Sky – Crescent Moon, Mercury, Regulus, and Orion

By Filed Under: Astronomy Images and Video

Late-summer sunrise from Bruneau Dunes State Park, Idaho.

After a cloudy night, the sky cleared as dawn arrived on a late summer morning as seen from Bruneau Dunes State Park in southern Idaho on September 8, 2018. Here you see a very slender waning crescent Moon to the upper left of the star Regulus. Mercury is at the lower middle of this image, just above the clouds. Just minutes earlier, the constellation Orion tried to peak through the early-morning clouds (see below) [Read more…] about Dawn Sky – Crescent Moon, Mercury, Regulus, and Orion

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