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Phil Harrington's Cosmic Challenge Archives

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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Cosmic Challenge: Stephan's Quintet

Oct 01 2017 10:56 AM | PhilH in Phil Harrington's Cosmic Challenge

The canvas on which our picture of the universe is painted relies on the unwavering acceptance of Hubble's Law. Hubble's Law states that a relationship exists between the distance to a galaxy and the speed at which it is receding from us. The farther away a galaxy is, the greater the speed of its recession and farther its spectral lines are shifted toward the red end of the spectrum. For Hubble's Law and the Red Shift Principal to be valid, it must work for not just a few galaxies, but for all. And indeed, it does -- well almost.

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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: 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: 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: Shadow Bands

Aug 03 2017 10:35 AM | PhilH in Phil Harrington's Cosmic Challenge

Enthusiasts think nothing of jetting around the world just to witness the few brief moments of a total solar eclipse. And with good reason, for all who behold the majesty of totality will give impassioned testimony to its unbridled glory. A total solar eclipse is the most beautiful and emotionally charged celestial event of all.

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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: 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: 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: 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: NGC 6803 and NGC 6804

Aug 07 2016 07:40 AM | PhilH in Phil Harrington's Cosmic Challenge

Here's a two'fer for you, a pair of challenges found within 1° of each other in the constellation Aquila the Eagle. Both of these planetary nebulae present interesting tests for smaller apertures, each in its own way.

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Cosmic Challenge: The Orion Galaxy

Feb 03 2018 10:06 AM | PhilH in Phil Harrington's Cosmic Challenge

You've heard of the Andromeda Galaxy and the Orion Nebula, but how about the Orion Galaxy? Probably not. But would you believe the New General Catalog lists 21 galaxies in Orion, and the Index Catalog adds another 9? That's a pretty respectable tally. Of those 30 Orion galaxies, I find this month's challenge particularly intriguing because it lies so close to everyone's favorite winter deep-sky object, M42. Yet, I am sure that very few observers have seen it.

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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: Alphabet Soup

Jan 02 2018 08:36 AM | PhilH in Phil Harrington's Cosmic Challenge

The Moon's terminator is a fascinating sight through all telescopes. Here, along the lunar sunset/sunrise line, lighting can strike familiar lunar features in very unusual ways, transforming them in ways that go unsuspected when the Sun rides high overhead.

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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: 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: Apollo Landing Sites

May 31 2019 11:46 AM | PhilH in Phil Harrington's Cosmic Challenge

Between July 1969 and December 1972, six teams of United States astronauts ventured across the gap between Earth and Moon to land and walk on that distant world. Have you ever visited their landing sites? If not, let's do so now.

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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: NGC 6886 and NGC 6905

Aug 29 2016 08:52 AM | PhilH in Phil Harrington's Cosmic Challenge

Last month, I offered up two planetary nebulae for smaller apertures. This month, we again hunt for a pair of planetaries. This time, however, we may need a little more oomph to get the job done.

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Cosmic Challenge: M51's spiral arms

Apr 30 2019 07:52 AM | PhilH in Phil Harrington's Cosmic Challenge

Of the thousands of spiral galaxies visible through backyard telescopes, one stands above the rest in terms of visual interest: M51, the famous Whirlpool Galaxy in Canes Venatici. Everything adds up in M51's favor. We are seeing it very nearly face-on, its spiral arm halo is bright and peppered with star clouds and vast regions of nebulosity, and it brings with it a friend in the form of a smaller companion galaxy that can even be seen through giant binoculars.

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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: 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: North America Nebula (NGC 7000)

Sep 01 2018 05:07 PM | PhilH in Phil Harrington's Cosmic Challenge

The North America Nebula (NGC 7000) is a large expanse of glowing hydrogen gas mixed with opaque clouds of cosmic dust just 3° east of Deneb [Alpha (α) Cygni] and 1° to the west of 4th-magnitude Xi (ξ) Cygni. Famous as one of the most luminous blue supergiants visible in the night sky, Deneb marks the tail of Cygnus the Swan, or if you prefer, the top of the Northern Cross asterism.

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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: Einstein's Cross

Oct 01 2018 08:53 PM | PhilH in Phil Harrington's Cosmic Challenge

From an aesthetic perspective, the most perfect gravitational lens is Einstein's Cross, formed by the galaxy PGC 69457 (cross- cataloged as CGCG 378-15) and the quasar QSO 2237+0305 in Pegasus. PGC 69457 is also known informally as Huchra's Lens after its discoverer, John Huchra, professor of cosmology Harvard University. Current estimates place this small, otherwise unspectacular spiral galaxy at 400 million light years away. The quasar lurks far behind at an incredible distance of 8 billion light-years. Were it not for gravitational lensing, the quasar would remain hidden by the galaxy, as the two are nearly in-line as seen from Earth. But as it is, Huchra's lens fractures the ancient light from the quasar into four separate paths that slide around the galaxy just as water flows around a rock in a stream. The end result is not one, but four ghostly images of QSO 2237+0305 surrounding the nucleus of PGC 69457 in a practically perfect diamond pattern.

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