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Phil Harrington's Cosmic Challenge Archives

Cosmic Challenge: Quasar 3C 273

May 01 2022 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Whenever my neighbor (I'll call him "Joe") sees me at one of my telescopes, he'll come over and ask "so, how far can you see with that thing?" Every time! You've also probably met someone like Joe. Well, unless you have a double-digit telescope, your answer should probably be "2.4 billion light years."

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Cosmic Challenge: Polarissima

Apr 01 2022 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

In astronomy, as in real estate, we have the Three Ls: location, location, location. NGC 3172 is a challenge for all seasons -- literally -- as its location keeps it above the horizon throughout the year no matter what time of night you are looking. That's because NGC 3172 lies within 1° of the North Celestial Pole, closer than any other NGC object.

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Cosmic Challenge: Beehive Galaxies

Mar 01 2022 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Hidden among the stars of M44 are no fewer than eight distant galaxies. Until 1987, most of us knew nothing of them. That was the year when the Uranometria 2000.0 star atlas was published. It showed the sky to a depth never before captured in a convenient star atlas format, and immediately shed light on thousands of objects that no amateurs, except possibly for a few extreme deep-sky hunters, even knew existed.

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Cosmic Challenge: Sirius and the Pup

Feb 01 2022 10:36 AM | PhilH in Phil Harrington's Cosmic Challenge

Ask an amateur astronomer to name binary stars that are difficult to resolve and one of the most common responses will probably be Sirius, in Canis Major. While there are more difficult targets, Sirius is always a perennial favorite. The challenge comes not from the close separation of the two stars in the system, however. Rather, the challenge here is from the extreme difference in the two stars' magnitude.

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Cosmic Challenge: Horsehead Nebula (Barnard 33)

Jan 01 2022 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Let's kick off the new year with what many consider to be one of the most difficult visual challenges in the sky. If you listen carefully, you might even hear the strains of the "Mission: Impossible" theme song playing in the background. Of all the deep-sky objects in the winter sky, none carries the mystique of the dark nebula Barnard 33, better known as the Horsehead Nebula.

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Cosmic Challenge: Abell Galaxy Cluster 373

Dec 01 2021 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Nestled in the southeast corner of the dim late-fall/early-winter constellation Fornax, adjacent to the distinctive triangle formed by 6th-magnitude Chi-1 (χ-1), Chi-2 (χ-2), and Chi-3 (χ-3) Fornacis, is an attractive cluster of galaxies known as Abell Galaxy Cluster - Southern Supplement (AGCS) 373.

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Cosmic Challenge: The Southern Pinwheel

Nov 01 2021 05:03 AM | PhilH in Phil Harrington's Cosmic Challenge

Have you ever heard of NGC 300, the Southern Pinwheel Galaxy? Were it positioned high in our autumn sky in a prominent constellation, you certainly would have. In fact, NGC 300, an Sc spiral tilted nearly face-on to our view, would be one of the season's showpieces, especially through large backyard telescopes. Because it lies in the far southern sky, nestled among the faint stars of Sculptor, it remains the purview of diehard deep-sky fanatics only.

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Cosmic Challenge: The Elephants Trunk

Oct 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Take a look at just about any star atlas and you will find a huge, irregular cloud of ionized hydrogen suspended to the south of Mu (μ) Cephei, Herschel's Garnet Star. That's IC 1396, one of the largest nebulae in the night sky. Even from a distance of about 2,450 light years, this complex cocktail of bright glowing gas mixed with dark dust clouds spans 3° of our sky. At that distance, 3° translates to a linear diameter of nearly 160 light years, more than three times greater than the Orion Nebula, M42.

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Cosmic Challenge: A Trio of Binaries

Sep 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

How close can two stars appear and still be resolvable as two? The single most important factor that influences the result is a telescope's aperture. All other things being equal, the larger the aperture, the finer the level of detail resolved. Of the many observational experiments that have been conducted to determine the resolution limits of telescopes, the two most often cited are the Rayleigh Criterion and the Dawes Limit.

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Cosmic Challenge: Planetary Nebula GJJC-1

Aug 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

What is your favorite globular cluster? Apart from those two southern hemisphere beauties, Omega (ω) Centauri and 47 Tucanae, my answer has to be M22 in Sagittarius. Admittedly, the star chains and "propeller" formation within M13 in Hercules (profiled in the July 2017 Cosmic Challenge) are visually intriguing. But there is just something about the remarkable richness of M22 and its surrounding star field that calls to me.

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Cosmic Challenge: Mons Hadley and Rima Hadley

Jul 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Fifty years ago this month, on July 30, 1971, Commander David Scott and Pilot James Irwin navigated their Apollo 15 lunar module, nicknamed Falcon, to land among the lunar Apennine mountains, while Alfred Worden remained in orbit aboard the command module, Endeavor. Scott and Irwin guided Falcon to a soft landing between the edge of a deep precipice and the base of a tall mountain to establish Hadley Base, as the landing site became known.

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Cosmic Challenge: Alcor and Mizar

Jun 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Is there any constellation in the sky more universally known than Ursa Major, the Great Bear? Most of us learned of it as a child, perhaps from a relative or friend, or possibly as a Scout working our way toward a merit badge in astronomy. The seven brightest stars in the group, known in North America as the Big Dipper or in England as the Plough, always draw our attention, especially in the spring when they ride highest in our sky.

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Cosmic Challenge: Markarian's Chain

May 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Aim your telescope anywhere in the large, seemingly empty gap between the stars Denebola [Beta (β) Leonis] and Vindemiatrix [Epsilon (ε) Virginis] and, given sharp eyes and a dark sky, you are bound to see one or more faint splotches of light somewhere in the eyepiece's field of view. You've entered the Coma-Virgo Realm of Galaxies, a collection of upwards

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Cosmic Challenge: Abell Galaxy Cluster (AGC) 1060

Apr 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Finding AGC 1060 is a simple task as long as you can spot 4.5-magnitude SAO 179041. This red giant sun overlaps the center of the cluster and lies 4¼° north of Alpha (α) Antliae. Of course, finding Alpha Antliae presents its own challenge, since it shines at only magnitude 4.2 and lies far from any handy reference stars.

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Cosmic Challenge: Zeta (ζ) Cancri

Mar 01 2021 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Although it is one of the faintest constellations along the zodiac, Cancer the Crab hosts a variety of targets to test our mettle during the early spring. Spotting M44, the Beehive Cluster, by eye alone may prove very challenging for suburban observers, while the Crab's underappreciated second open cluster, M67, may also reach naked-eye visibility from more rural environs. While the constellation boasts a variety of challenging galaxies, in the test here, we will try our luck with one of the constellation's prettiest binary stars, Zeta (ζ) Cancri.

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Cosmic Challenge: NGC 2438

Feb 01 2021 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

M46 in Puppis is one of my favorite open clusters and a striking sight through just about any telescope. More than 500 stars are crammed into an area just a Moon's diameter across, creating one of the most jam-packed throngs in the winter sky.

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Cosmic Challenge: Simeis 147

Jan 01 2021 07:00 AM | PhilH in Phil Harrington's Cosmic Challenge

The year 1054 must have been an active one for stargazers. That was the year that the famous Crab Nebula supernova blasted forth, shining brightly enough for Chinese and Native American skywatchers to note a "new star" blazing near what we now call the tip of one of Taurus the Bull's two horns. The 1054 supernova was so bright that it was visible in broad daylight during the summer of that year and remained visible to the naked eye for nearly a year. Today, we know the fading gaseous remnant of that all-consuming event as the Crab Nebula, M1.

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Cosmic Challenge: NGC 1360

Dec 01 2020 01:01 PM | PhilH in Phil Harrington's Cosmic Challenge

Many stargazers consider Fornax, the Furnace, to be a constellation of the deep south, and therefore, invisible from mid-northern latitudes. While it is true that Fornax scrapes the southern horizon on early winter evenings, it does so at much the same altitude as Scorpius does during the summer. If you can see Scorpius from your observing site in July, you can see Fornax tonight. Assuming it's clear, of course!

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Cosmic Challenge: The Eye of Mars

Nov 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

With Mars just having passed opposition on October 13, I thought it might be fun to challenge you to see a specific surface feature on the Red Planet before it slips too far away.

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Cosmic Challenge: Spotting Uranus

Oct 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

On March 12, 1781, the solar system was a simple, very well-behaved place that was best summed up with the phrase "what you see is what you get." There were the Sun, the Moon, and the five planets: Mercury, Venus, Mars, Jupiter, and Saturn. Apart from a handful of moons orbiting some of the planets and the occasional faint comet that required a telescope to be seen, the entire contents of the solar system was naked-eye territory.

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Cosmic Challenge: Ring Nebula Central Star and Galaxy IC 1296

Sep 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

As we say goodbye to summer and get ready to welcome in autumn, I thought I would offer not one, but two challenges this month to bridge the seasonal change. Both appear right next to each other in our sky but are millions of light years apart. And both require all the aperture you can throw at them to be seen.

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Cosmic Challenge: NGC 6445, The Box Nebula

Aug 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

The sky is full of weird sights. And among planetary nebulae, NGC 6445 is one of the strangest. Discovered by William Herschel on May 28, 1786, NGC 6445 shines at 11th magnitude. That's bright enough to be seen even through giant binoculars. Although visible in smaller apertures, it takes a 6-inch telescope for NGC 6445's true, if bizarre, nature to shine through. The nebula's brighter central shell looks like a dented rectangle. Nature rarely creates an amorphous form with sharp edges, and indeed, the peculiar appearance of NGC 6445 is due largely to our perspective as well as its age. But the look is very odd nonetheless. No wonder NGC 6445 has been nicknamed the Box Nebula.

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Cosmic Challenge: Seyfert's Sextet

Jul 06 2020 03:00 PM | PhilH in Phil Harrington's Cosmic Challenge

Seyfert's Sextet, known to many as Hickson Compact Galaxy Group 79, is a tight gathering of galaxies in the northern corner of Serpens Caput. Serpens Caput is the western segment of this bisected constellation, marking the triangular head of the serpent that Ophiuchus is handling. Observing Seyfert's Sextet has been one of my pet projects for years. It's a fun little galactic rat pack for summer outings before we plunge headlong into the summer Milky Way.

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Cosmic Challenge: Rupes Recta (Straight Wall), Huygen's Sword, Birt, and Rima Birt

Jun 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

What is your favorite lunar feature? Maybe it's the mighty craters Copernicus or Tycho. Or could it be the historic Sea of Tranquility? Perhaps you enjoy visiting the rugged southern highlands around Clavius, or the Apennine and Alp Mountains. If I had to come up with my favorite target, it would have to be a far more modest sight. I always enjoy looking for and at the Straight Wall.

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Cosmic Challenge: Two Pairs

May 01 2020 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Most agree that the Messier catalog of deep-sky objects stands as the finest single compilation of star clusters, nebulae, and galaxies visible from the northern hemisphere. When it comes time to single out the finest of the list's 109 entries, however, we often have trouble agreeing. Is it the Orion Nebula, M42; the Great Globular Cluster, M13; or maybe the Ring Nebula, M57? So many choices! One thing is for certain -- you'll never find Messier's 40th entry on anyone's "finest" list.

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