Cosmic Pursuits

Basic astronomy and night sky information

Deep Sky Observing

Articles about how to understand, find, and see celestial objects including stars, galaxies, nebulae, and star clusters with binoculars, telescopes, and the naked eye.

A Speedy Little Double Star

by Brian Ventrudo Filed Under: Deep Sky

An image of 70 Ophiuchi by Damian Peach.

When it comes to observing the stars and other sights beyond our solar system, there’s always something new to see. But once you see it, chances are it’s not going to chance much in the coming years. That’s because things move slowly in the cosmos, at least compared to a human lifetime.

There are, however, a few exceptions. One of the most important for astronomers is the nearby binary star called 70 Ophiuchi, a little gem in the asterism known as Taurus Poniatowski in the constellation Ophiuchus. It’s a beautiful star for casual stargazers armed with a small telescope. Serious stargazers can watch over the course of a year or two to detect the motion of the two components as they slowly revolve around each other during their 88-year period. It’s one of the few double stars that make a complete revolution within the course of a human lifetime [Read more…] about A Speedy Little Double Star

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The Blue-Green Beauty of Planetary Nebulae

by Joe Bergeron Filed Under: Deep Sky

A long-exposure image of the Helix Nebula (NGC 7293) shows far more color than can be observed visually, even through a large telescope. Image credit: Terry Hancock.

New and would-be amateur astronomers are often mystified and disappointed by the lack of color in things they see through their telescopes. And why shouldn’t they be? Popular astronomy shows, magazines, and web sites encourage people to believe that celestial objects are rich with blistering, saturated color, much like the image above. Why doesn’t that new $400 8-inch Dobsonian show bright pink nebulae, and galaxies of blue and gold? [Read more…] about The Blue-Green Beauty of Planetary Nebulae

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Orion, Above the Belt

by Brian Ventrudo Filed Under: Deep Sky

NGC 2175, the Monkey Head Nebula. Credit: Paul Hutchinson via Flickr.

Orion is perhaps the most famous of the 88 constellations in the night sky, and it’s likely the easiest to find for stargazers all over the world.  And unlike most constellations, Orion looks like its legendary namesake: a mighty hunter with a shield, a raised arm, and a sword hanging from his star-jeweled belt. The constellation harbors some dazzling sights including what may be the most beautiful object in the night sky for a small telescope, the famous Orion Nebula, a bright blister in the nearest star-forming region to our solar system. In this little tour, we’ll have a look at some lesser-known sights in the constellation Orion north of the three bright stars of Orion’s Belt [Read more…] about Orion, Above the Belt

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Roaming the October Skies – A Brief Tour of Aquarius

by Brian Ventrudo Filed Under: Deep Sky

The Helix Nebula is a planetary nebula, a cloud of glowing gas ejected by a dying mid-sized star. (Image by Terry Hancock)

Aquarius is a dim constellation in a barren patch of sky far off the plane of the Milky Way. Just east of Capricorn, it marks the 11th constellation of the zodiac. This dim constellation lies near the other “watery” constellations including Cetus, the Sea Monster (or whale), Pisces, the Fishes, and Eridanus, the River. This ancient constellation was associated with water or water bearers since Babylonian times. Some representations have the water bearer pouring water into a stream that leads to the bright star Fomalhaut, the mouth of the southern fishes Piscis Austrinus. Like Capricorn, Aquarius has far fewer deep-sky sights than Sagittarius. But there are a handful of objects here of enduring interest including the famous Helix Nebula, one of the nearest planetary nebulae to Earth. Let’s take a short tour of some of the finer sights in this zodiacal constellation… [Read more…] about Roaming the October Skies – A Brief Tour of Aquarius

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Seeing Carbon Stars, Close Up and Far

by Brian Ventrudo Filed Under: Deep Sky

his ALMA image reveals much finer structure in the U Antliae shell than has previously been possible. Around 2700 years ago, U Antliae went through a short period of rapid mass loss. During this period of only a few hundred years, the material making up the shell seen in the new ALMA data was ejected at high speed. Examination of this shell in further detail also shows some evidence of thin, wispy clouds known as filamentary substructures. Credit: ALMA (ESO/NAOJ/NRAO)/F. Kerschbaum

Many experienced stargazers are connoisseurs of carbon stars, deep-red and highly evolved stars that are dredging up carbon and other nuclear reactants from their innards on their way to becoming, briefly, planetary nebulae. These striking stars are the most colorful of all celestial sights and they’ve long intrigued astronomers who are trying to fine tune their theories of how stars come to the end of their lives. Carbon stars are too far away to reveal much detail directly, so astronomers study them indirectly by examining their spectra. But a team of researchers at the remarkable ALMA telescope in northern Chile have captured an amazingly beautiful and revealing image of a carbon star in the constellation Antlia. Let’s have a look at what they saw, then set some time aside to go see a carbon star for ourselves with a small telescope or pair of binoculars [Read more…] about Seeing Carbon Stars, Close Up and Far

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