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Phil Harrington's Cosmic Challenge Archives

Cosmic Challenge: Globular Clusters in the Fornax Dwarf Galaxy

Dec 03 2016 07:13 AM | PhilH in Phil Harrington's Cosmic Challenge

Let's begin this challenge with a riddle. What's big and round, close at hand, and yet nearly impossible to see? If you answered "the Fornax Dwarf Galaxy," then you are correct! The Fornax Dwarf, a dwarf spheroidal system, covers a 17'x13' area of our late autumn sky and lies about 530,000 light years from the Milky Way. That's well within the confines of our Local Group of galaxies. And with a magnitude rating of 9.3, it sounds like it should be bright and easy to see. But when we look its way, it's not there. Even the best photos manage to record only an incredibly dim, elliptical haze peppered by some 19th-magnitude stars!

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Cosmic Challenge: Barnard's Loop

Dec 31 2016 08:20 AM | PhilH in Phil Harrington's Cosmic Challenge

One of the greatest naked-eye challenges goading amateur astronomers around the world is trying to spot the elusive arc of nebulosity known as Barnard's Loop. Cataloged officially as Sharpless 2-276, Barnard's Loop is a ghostly, 10°-wide semicircular bow of nebulosity that wraps around the eastern side of Orion, the Hunter. In long exposure photographs, it bears the unmistakable resemblance to portions of the Veil Nebula supernova remnant in Cygnus. Spotting it by eye stands as a monumental test for observers.

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Cosmic Challenge: A Case of Mistaken Identity

Feb 04 2017 07:53 AM | PhilH in Phil Harrington's Cosmic Challenge

There once was a mystery in Lynx. The story opened in 1790 when William Herschel discovered a small, nebulous glow about 2½° northwest of 27 Lyncis. He later added it as number 830 in his list of "very faint nebulae" (abbreviated H-III-830) and apparently moved on without noticing a second, fainter blur of light just to the northeast. That second object was discovered 66 years later by William Parsons, 3rd Earl of Rosse, through his 72-inch "Leviathan" reflector. Both were later incorporated into John Dreyer's New General Catalog. NGC 2474 is described as "faint, pretty small, extended?, brighter middle, very small star?, large star north following." NGC 2475 is simply noted as "makes a double nebula with" NGC 2474.

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Cosmic Challenge: Jonckheere 900

Mar 04 2017 08:03 AM | PhilH in Phil Harrington's Cosmic Challenge

Few amateur astronomers are familiar with the name Robert Jonckheere. Jonckheere was a French double-star observer who conducted research at a number of observatories over his six-decade career, including the Strasbourg Observatory in France, the Royal Greenwich Observatory in England, as well as McDonald Observatory in Texas.

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Cosmic Challenge: Leo I

Apr 01 2017 11:21 AM | PhilH in Phil Harrington's Cosmic Challenge

Seven decades ago, while scanning a Palomar Sky Survey plate of the area around brilliant Regulus in Leo the Lion, astronomers Robert Harrington (no relation) and A.G. Wilson noticed a faint blur of light just 1/2° north of the star. They may have thought at first that the glow was just an internal lens flare caused by stray starlight, but it soon became apparent that they had discovered something very real.

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Cosmic Challenge: Lunar Craters Messier and Messier A

May 31 2017 01:20 PM | PhilH in Phil Harrington's Cosmic Challenge

Summer is in the offing here in the Northern Hemisphere and the longest day of the year is at hand. While many of us enjoy the warmer weather, the dark of night comes late in the evening and leaves all too early the following morning. So while deep-sky observing is limited, we can still enjoy viewing our Moon even if the sky is still bright. Yes, observing challenges await us on our nearest neighbor in space.

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Cosmic Challenge 61 Cygni: Piazzi's Flying Star

Sep 01 2017 09:48 AM | PhilH in Phil Harrington's Cosmic Challenge

The star 61 Cygni is not bright, nor is it visually distinctive. To the eye alone, it looks just like any other 5th-magnitude point of light deep in the Milky Way flowing through the Swan. But looks can be deceiving! This unremarkable looking star is indeed quite remarkable for its unusually high rate of proper motion. By watching and plotting it against the backdrop of stars over the course of relatively few years, its position shifts at an extraordinarily fast pace. At present, 61 Cyg has a proper motion of more than 5 arc-seconds per year.

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Cosmic Challenge - NGC 404

Nov 17 2017 08:36 PM | PhilH in Phil Harrington's Cosmic Challenge

Did you know that I discovered a comet in the fall of 1973? I was out with my venerable 8-inch Criterion RV-8 Dynascope Newtonian reflector, just hopping around the autumn sky, when I noticed stars weren't focusing sharply. Thinking the telescope's collimation was off, I aimed at a nearby bright star to check whether the silhouette of the secondary mirror was centered correctly in the star's out-of-focus image. After I tweaked things a bit, all appeared well, so I focused on that star to check things before moving on. Lo and behold, I saw a dim blur of light right next to the star! Checking things further, it wasn't an internal reflection or an optical aberration.

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Cosmic Challenge: Abell Galaxy Cluster 426

Dec 07 2017 06:02 AM | PhilH in Phil Harrington's Cosmic Challenge

Not long after I got my first "good" telescope, my 8-inch Criterion RV-8 Dynascope Newtonian reflector, as my Christmas gift in 1971, I became fascinated with the Perseus Galaxy Cluster. One reason I am so fond of this collection of more than 500 galaxies is that the cluster grows as the telescope's aperture increases. Small backyard scopes will show the two big kids on the block, NGC 1272 and NGC 1275, but even the largest amateur instruments fail to show all of the "little guys."

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Cosmic Challenge: NGC 2419

Mar 04 2018 08:21 AM | PhilH in Phil Harrington's Cosmic Challenge

Probably known better by its nickname the "Intergalactic Tramp" bestowed by Harlow Shapley in 1944, NGC 2419 is unusual among winter's deep-sky objects for many reasons.

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Cosmic Challenge: Leo II

Mar 31 2018 09:54 AM | PhilH in Phil Harrington's Cosmic Challenge

Last April, this column profile the dwarf spheroidal galaxy Leo I, discovered by chance in 1950 by astronomers Robert Harrington (still no relation!) and A.G. Wilson as they were scanning the Palomar Sky Survey. I ended that column saying that "Using the right eyepiece and knowing the field will help you add this dwarf spheroidal to your list of conquered challenges with comparative ease. But don't get too cocky. Spotting its sibling, Leo II is an even greater challenge. But we will leave that for a future column." Well, that future is now.

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Cosmic Challenge: M109

May 01 2018 05:20 AM | PhilH in Phil Harrington's Cosmic Challenge

Messier did not live to see a second edition of his catalog, but objects 104 through 110 have been added posthumously by others. M109 joined the ranks in 1953, when astronomy historian Owen Gingerich noted Messier's observations of six additional "Méchain objects," now known as M104 through M109.

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Cosmic Challenge: Glimpsing Vesta

Jun 01 2018 06:34 AM | PhilH in Phil Harrington's Cosmic Challenge

Vesta turns out to be more like a mini-planet than like the chunks of rock most think of as asteroids. Dawn's measurements of the gravity field provided good evidence that Vesta's interior is separated into layers, much like Earth did as the planet was forming. Vesta's dense core - apparently once molten, but now solidified - is composed principally of iron and nickel, just like Earth's. Estimates place it at 125 to 150 miles (200 to 250 kilometers) across. Surrounding that is the mantle, which in turn is covered by the veneer of the crust, about 12 miles (20 kilometers) thick. It is now believed that early on Vesta was likely still accumulating material to become a full-fledged planet when Jupiter's immense gravity intervened, putting a stop to that. As a result, when we look at Vesta, many believe that we are seeing a protoplanet frozen in time.

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Cosmic Challenge: NGC 147 and NGC 185

Nov 04 2018 08:46 AM | PhilH in Phil Harrington's Cosmic Challenge

M32 and M110 are nice challenges for handheld binoculars. Most amateurs are familiar with them, since they lie in the same field of view of the parent Andromeda Galaxy. But two others, designated as NGC 147 and NGC 185, are not as nearly well known. Both are several degrees to M31's north, across the border in Cassiopeia and feature smaller, fainter disks that are much more challenging to see.

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Cosmic Challenge: Globular clusters in M31

Dec 01 2018 06:00 AM | PhilH in Phil Harrington's Cosmic Challenge

The Andromeda Galaxy, M31, was probably one of the first galaxies you ever saw first-hand. It was mine. That was all way back in 1969. Since then, I have grown to appreciate it as far more than just the ill-defined oval blur I drew in my logbook. But in 1969, the thought of looking for individual objects within M31 never crossed my mind.

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Cosmic Challenge: Jonckheere 320

Jan 01 2019 06:04 AM | PhilH in Phil Harrington's Cosmic Challenge

On January 22, 1916, while revisiting some of the stars in his Catalog and Measures of Double Stars discovered visually from 1905 to 1916 within 105° of the North Pole and under 5" Separation, French astronomer Robert Jonckheere returned to a vague double in Orion, which he had previously designated as entry number 320. Jonckheere was later to write of this encounter through the 28-inch refractor at the Royal Greenwich Observatory, "I noticed that the object I have catalogued as J 320 is not a double star, but, like J 475, it appears with the larger instrument to be an extremely small bright elongated nebula. As is the case with J 900, this object also appears to be new as a nebula."

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Cosmic Challenge: Leo III

Mar 30 2019 09:54 AM | PhilH in Phil Harrington's Cosmic Challenge

A springtime rite of passage started here two years ago. It started in the April 2017 edition of this e-column, when I challenged readers to find the dwarf galaxy Leo I. Leo I is one of many dim dwarf galaxies gravitationally bound to the Milky Way. The fact that its surface brightness rates only 15th magnitude, coupled with its position just 20' north of Regulus makes Leo I a tough challenge to land.

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Cosmic Challenge: Planetary nebula IC 4732

Aug 01 2019 04:55 AM | PhilH in Phil Harrington's Cosmic Challenge

M22 is right in the thick of it, not far from the galactic center of the Milky Way. As such, it has lots of company. One particular planetary nebula proves a worthy adversary through 10- to 14-inch scopes: IC 4732. IC 4732 lies just 1.4° north-northwest of M22. Cataloged at magnitude 12.1, its tiny disk is difficult to pick out from the mob of field stars -- difficult, but not impossible.

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Cosmic Challenge: Emission Nebula Simeis 57

Sep 01 2019 10:16 AM | PhilH in Phil Harrington's Cosmic Challenge

Simeis 57 is one of the most intriguing emission nebulae in the late summer sky, yet it is almost unknown to visual observers. Photographers, however, know it as a pair of opposing arcs of reddish light, one extending to the north, the other to the south, that appear to be spinning symmetrically away from a common center. Its unusual appearance has led to its two nicknames: the Propeller Nebula or the Garden Sprinkler Nebula.

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Cosmic Challenge: The Deer Lick Group

Oct 01 2019 05:03 AM | PhilH in Phil Harrington's Cosmic Challenge

The autumn sky abounds with little bundles of galaxies scattered throughout its stars. One of the best known is the group of 7 galaxies that surround the magnificent spiral NGC 7331 in Pegasus, the Flying Horse. An observer could easily spend an hour or more just soaking in all that this small patch of sky has to offer.

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Cosmic Challenge: Galaxies around M13

Jun 26 2016 11:00 AM | PhilH in Phil Harrington's Cosmic Challenge

If you're like me, you have probably seen Jupiter, Saturn, the Orion Nebula, and all of the sky's showpiece objects more times than you can count. And while they are truly spectacular and well worth revisiting, you may be looking for something new, something challenging to observe.

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Cosmic Challenge: Pease 1

Oct 01 2016 03:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Of the more than 130 globular clusters gravitationally linked to our Milky Way galaxy, only four are known to contain planetary nebulae.  The best known example of a planetary/globular pairing is Pease 1 found within M15 in Pegasus.  That's this month's Cosmic Challenge.

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Cosmic Challenge: IC 5146 and B168

Oct 29 2016 08:17 AM | PhilH in Phil Harrington's Cosmic Challenge

As a group, emission nebulae, or Hydrogen-II regions, are the most difficult deep-sky objects to see visually. The problem is that they radiate light in very narrow segments of the visible spectrum, with their brightest emissions in the red wavelengths. As luck would have it, the human eye is all but color blind to red light under dim light conditions. Arguably, the only objects more difficult to spot than emission nebulae are the opaque profiles of dark nebulae. These cosmic dust clouds are themselves invisible; we only see their silhouettes against the starry backdrop. No starry backdrop, no dark nebula; it's that simple. And that brings us to this month's double challenge in Cygnus. IC 5146, known to many by its nickname, the Cocoon Nebula, is a taxing patch of glowing gas, while Barnard 168 is a thin, sinuous lane of darkness that seems to start at the nebula and extend far to its northwest.

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Cosmic Challenge: The Antennae

May 01 2017 12:45 PM | PhilH in Phil Harrington's Cosmic Challenge

Seven decades ago, while scanning a Palomar Sky Survey plate of the area around brilliant Regulus in Leo the Lion, astronomers Robert Harrington (no relation) and A.G. Wilson noticed a faint blur of light just 1/2° north of the star. They may have thought at first that the glow was just an internal lens flare caused by stray starlight, but it soon became apparent that they had discovered something very real.

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Cosmic Challenge: M13's propeller

Jul 01 2017 09:33 AM | PhilH in Phil Harrington's Cosmic Challenge

In last month's column, we paid a visit to the Moon and the crater pair of Messier and Messier A. This month, we head back out into deep space to examine one of the most spectacular entries in Charles Messier's catalog: M13, the Great Hercules Globular Cluster.

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