Glenn Chaple

Glenn Chaple

I've been an avid backyard astronomer since the early 1970s and a member of the Amateur Telescope Makers of Boston (ATMoB and the American Association of Variable Star Observers (AAVSO) since 1980. I currently write the monthly "Observing Basics" column for Astronomy.

Last updated: August 6, 2012
M104: The Sombrero Galaxy

M104: The Sombrero Galaxy

One of the more noteworthy examples of an edge-on spiral galaxy bisected by a dark dust lane is M104, the Sombrero Galaxy. The nick-name arises from the galaxy’s resemblance to the traditional Mexican headwear, the bright nuclear bulge forming the hat and the spiral arms/dust lane the wide brim.
M101: Spiral Galaxy in Ursa Major

M101: Spiral Galaxy in Ursa Major

One of the best examples of a star-hop is the one that takes us from Mizar (the middle star in the Handle of the Big Dipper) to the face-on spiral galaxy M101. It’s a fortuitous situation because, were it isolated, M101 might be one of the more difficult Messier objects to locate.
M78: Reflection Nebula in Orion

M78: Reflection Nebula in Orion

It’s understandable that M78 should be overlooked by backyard astronomers. Not far away is the much brighter, much more easily found, and much, much more spectacular M42 - the Orion Nebula. This deep-sky masterpiece was spectacular even through the eyepiece of my 3-inch scope. M78, on the other hand, was a faint blob that seemed to sport an off-center nucleus.

NGC 7662: the Blue Snowball

What could be a more appropriate telescopic destination for a wintry night in January than the “Blue Snowball?” More formally known as NGC 7662, the Blue Snowball is a beautiful planetary nebula located in Andromeda. Discovered by William Herschel in 1784, it sports as the nickname implies a circular form and eye-pleasing bluish hue.
Maserthim (γ Arietis)

Maserthim (γ Arietis)

I’m a double star aficionado; my sky gazing motto is “double stars are twice the fun!” Unlike the “faint fuzzies” most backyard astronomers prefer, double stars aren’t hidden by light pollution or bright moonlight. They aren’t the exclusive property of big-scope owners. In fact, many showpiece doubles are within reach of small-aperture instruments. The common 60mm refractor with its crisp stellar images delivers exquisite views of double stars - especially twin systems.

Struve 2816 and 2819: Triple and Double Stars in Cepheus

There’s something hypnotic about a double star – two gleaming points of light shining bravely through the surrounding darkness. A triple star is even more mesmerizing. Place a double star and triple star in the same eyepiece field, and the visual effect is stunning. This is what greets the eye when you view the triple/double star combo Struve 2816 and Struve 2819.

NGC 6934: Globular Cluster in Delphinus

October sees the demise of the summer Milky Way and its swarm of globular clusters centered on the constellation Sagittarius. A few, notably M15 in Pegasus, lag behind to grace our autumn skies. Another of these stragglers is NGC 6934 in Delphinus. This small 9th magnitude globular was discovered by William Herschel in 1785. In early star atlases and in modern-day “Herschel 400” guides, it bears the designation H1031 - the 103rd entry in Category I (bright nebulae) of Herschel’s deep sky catalog.
Coathanger Asterism in Vulpecula

Coathanger Asterism in Vulpecula

If you slowly scan the southern part of Vulpecula with binoculars or rich-field telescope, you’ll come across a remarkable asterism comprised of 10 stars arranged in the distinct form of a coathanger. Six line up to form the bar, while four others create the hook. It’s quite an eye-opening sight!
M22: Globular Cluster in Sagittarius

M22: Globular Cluster in Sagittarius

What’s the most spectacular globular cluster in the northern sky? Most backyard astronomers would pick the Great Cluster M13 in Hercules. If you wish to view the finest globular cluster visible from the entire New England sky, however, you’ll have to travel south of the celestial equator to the constellation Sagittarius and its showpiece globular cluster M22.
The Lunar X

The Lunar X

Some of the more intriguing lunar sights are transient features - short-lived phantoms formed by shadows cast by crater rims or by high-altitude areas capturing the glint of the rising sun. Many of these occur near the lunar terminator. One of the most remarkable is the “Lunar X” which appears around the time of first quarter moon.
Porrima: Binary Star in Virgo

Porrima: Binary Star in Virgo

Compiling a list of the finest double stars for backyard telescopes is always a work in progress. The list is forever in flux, because many showpiece double stars are binary systems that periodically close to the point where they can’t be resolved by small-aperture telescopes. Such is the case with Porrima (gamma [γ] Virginis).
Algieba: Double Star in Leo

Algieba: Double Star in Leo

One of the finest double stars in the spring sky – indeed, in all the heavens – is gamma (y) Leonis. Its proper name, Algieba, comes from the Arabic Al Jabbah (The Lion’s Mane).
Variable Star R Leonis

Variable Star R Leonis

On the evening of March 1, 1918, a young Ohio farm boy trained a small refracting telescope towards the variable star R Leonis. He estimated its brightness, later forwarding the information to the American Association of Variable Star Observers. It was the first of over 132.000 variable star observations the legendary Leslie Peltier would submit to the AAVSO.

433 Eros

Very rarely does a near-earth asteroid become bright enough to be seen with small backyard scopes. A notable exception is the asteroid 433 Eros. Around the time of its nearest approach on January 31, Eros will be 16.6 million miles from Earth.

M74: Galaxy in Pisces

Last month, we explored the galaxy M33, a notoriously difficult telescopic target due to its extremely low surface brightness. For the same reason, M74 is even more challenging; in fact, many consider it the most visually demanding of all the Messier objects.

M33: Galaxy in Triangulum

Consider the spiral galaxy M33 in Triangulum. Listed as a 6th magnitude object, it’s notoriously difficult to view in telescopes. M33 is elusive because its light is spread over an area four times that of the full moon.

Almach

Last month, I suggested that our featured object, Albireo, may not be the most beautiful double star in the sky and I’d introduce a rival this month. If you guessed that Albireo’s challenger is Almach, the gamma (?) star in Andromeda, you’d be correct!

β Cygni (Albireo)

I’m a big fan of “off-the-beaten-path” sky objects. One of my favorites is the little-known double star Struve 817 - the 817th double star catalogued by the German-born Russian astronomer F. G. W. Struve during a survey conducted between 1824 and 1827.

M56: Globular Cluster in Lyra

In July, we looked at M92, a fine globular cluster in Hercules that’s overlooked in favor of the easier-to-find M13. The same misfortune has befallen another globular cluster - M56 in Lyra. M56 is often bypassed by backyard astronomers who favor the planetary nebula M57, conveniently positioned midway between the stars beta (β) and gamma (γ) Lyrae.

M92: Globular Cluster in Hercules

Quick question. How many times (to the nearest thousand) have you viewed the great globular cluster M13 with your telescope? Next question. How many times (nearest thousandth) have you visited Hercules’ other great globular cluster M92? I doubt it would be an exaggeration to say that I’ve seen M92 once for every hundred times I’ve viewed M13.
β Scorpii

β Scorpii

This month, we travel southward to the constellation Scorpius and the showpiece double star beta (β) Scorpii, also known as Graffias. Beta Scorpii is an eye-pleasing pair of magnitude 2.6 and 4.5 stars separated by 13.6 arc-seconds. The magnitudes and separation are quite similar to those of the better-know Mizar; indeed, Graffias rivals Mizar in visual splendor.

3C 273: Quasar in Virgo

“How far can you see with that telescope?” It’s a question I occasionally hear from visitors who peer into my telescope at public star parties. The farthest my telescopes have taken my eye, I tell them, is 2 billion light years - to the quasar 3C 273.

NGC 2903: Spiral Galaxy in Leo

To the deep-sky aficionado, spring means one thing – galaxies. Dozens of these island universes are within the grasp of small-aperture telescopes, while a 10-inch Dob can corral thousands. The constellation Leo is home to some of the brighter spring galaxies, including five listed in the Messier Catalog. One, however, escaped the eye of the French comet-hunter, even though it’s visible in binoculars from dark-sky locations.

Castor: alpha (α) Geminorum

Are you looking for something new and different to add to your late winter/early spring star party repertoire – a cosmic showpiece guaranteed to elicit a gasp of surprise and wonder from anyone who peers into your telescope? I suggest the double star alpha (α) Geminorum, better know as Castor. One glance at these sparkling magnitude 2.0 and 2.9 diamonds and it’s easy to understand why William Herschel’s son, John, considered Castor the finest double star in the northern sky.

β Monocerotis

Observe one of the sky's best triple stars just 12 degrees east of the Great Orion Nebula.
NGC 457 (the “ET Cluster”)

NGC 457 (the “ET Cluster”)

Have you seen “ET” lately? Not that cute little alien in Steven Spielberg’s 1982 movie. I’m referring to the ET-mimicking open star cluster NGC 457 in Cassiopeia. Discovered by William Herschel in 1787, NGC 457 is often overlooked because of its proximity to the Messier cluster M103.
Delta (δ) and Mu (μ) Cephei

Delta (δ) and Mu (μ) Cephei

In the southern part of Cepheus is a pair of naked eye variable stars worthy of note. The first, delta (?), is the prototypical Cepheid variable. It ranges between magnitudes 3.5 and 4.4 in a precise 5.37 day period. The rise from minimum to maximum brightness takes about 1½ days; the fade back to minimum involves an additional four.

The Milky Way

Many astronomers regard the Milky Way, viewed with the unaided eye on a dark, moonless night, as the most awe-inspiring heavenly sight of all. During late summer, it arches overhead, from Cassiopeia to our north, through Cygnus above, then down to Sagittarius on the southern horizon.

IC 4665

One reason for IC 4665’s relative anonymity is its large size, allowing it to elude the narrow fields of large-aperture telescopes. Charles Messier and William Herschel missed it, and it wasn’t included in the New General Catalogue. This often-overlooked cluster is definitely a must-see object for binoculars and rich-field telescopes.

NGC 6207

Most backyard astronomers are so entranced by the Great Hercules Cluster M13 that they fail to notice a small, faint oval patch of light a half degree to the northeast. This is the 11th magnitude galaxy NGC 6207.

Izar (ε Boötis)

A larger telescope and magnifying power of 200X will readily split Izar and reveal a striking color contrast between the golden yellow primary and its bluish companion. The Russian astronomer Wilhelm Struve, who conducted a double star survey in the late 1820s and early 1830s, nick-named it “Pulcherrima” (The Most Beautiful).

M40: The “Unknown” Messier Object

Arguably the oddest member of the Catalog, M40 isn’t a cluster, nebula, or galaxy. It’s a double star! We might well label M40 “Messier’s Mistake.”

Sirius

Next time you set out to do some “serious” astronomy, try a moment to make a “Sirius” observation. You’ll be delighted you did.

h 3945 Canis Majoris

What is the most colorful double star in the night sky? Most amateur astronomers would vote for β Cygni (Albireo). Others might cite γ Andromedae (Almach), ι Cancri, ξ Bootis, or η Cassiopeiae. Sadly overlooked is a double star that might challenge them all – h 3945 in Canis Major. It is arguably the most colorful double star in the winter sky and, in fact, has been nick-named the “Winter Albireo.”

Beta Orionis (Rigel)

You won’t need a finder chart to locate this month’s featured sky object. It’s the first magnitude star β Orionis, better known by its proper name Rigel. Seventh brightest star in the night sky, Rigel dazzles us with a diamond-white color; especially striking when compared with Orion’s other first-magnitude star, the ruddy-hued Betelgeuse.

Omicron Ceti (Mira, the “Wonderful”)

Last month, we looked at the prototypical eclipsing binary beta Persei (Algol). This month, we turn to another prototype, the classic long-period variable (LPV) omicron Ceti.

Beta Persei (Algol, the "Demon Star")

Are you ready for the eclipse of November 13th? I’m not talking about the sun or moon. I’m referring instead to an eclipse of the fascinating star ß Persei (Algol).
NGC 7293: the Helix Nebula

NGC 7293: the Helix Nebula

NGC 7293, the Helix Nebula, is the nearest planetary nebula (distance ~ 450 LY) and largest in apparent size (12 by 16 arcminutes). Moreover, it’s a 7th magnitude object. An easy telescopic target? Hardly! The magnitudes listed for deep-sky objects are often misleading, and the Helix Nebula is a prime example.

Epsilon Pegasi: The Pendulum Star

Epsilon Pegasi (Enif) is an optical double star comprised of magnitude 2.5 and 8.7 component stars separated by 144 seconds of arc. Pairs this wide usually don’t merit much consideration, but wait! Epsilon Pegasi has a surprise for us.

Chaple’s Arc

Forgive me for the apparent ego trip, but this month I’m going to introduce you to an amazing little asterism called “Chaple’s Arc.” I stumbled upon the Arc in the mid-1970s while looking for the double star h1470.

Messier 6 and Messier 7

The song “Love and Marriage,” contains a line that goes, “you can’t have one without the other.” The words aptly describe the open clusters M6 and M7 in Scorpius. This cosmic “horse and carriage” lies in the southern sky above the Scorpion’s stinger.

44 Boötis

44 Boötis, whose 210-year orbit is highly inclined to our line-of-sight, has opened up. Its magnitude 5.3 and 6.2 component stars are separated by 2.2 arc-seconds.
Mizar, The First Double Star

Mizar, The First Double Star

The middle star in the handle of the Big Dipper, Mizar is the easiest double star for the novice to locate. It boasts historical importance as the first double star discovered.

Struve 817 Orionis

I’m a big fan of “off-the-beaten-path” sky objects. One of my favorites is the little-known double star Struve 817 - the 817th double star catalogued by the German-born Russian astronomer F. G. W. Struve during a survey conducted between 1824 and 1827.

A Selection of Double Stars in Andromeda

Andromeda is home to a fine collection of double stars. Here are eight of the best. Data on magnitudes and separation were taken from the Washington Double Star Catalog.

A Selection of Double Stars in Draco

A hazy summer evening may prevent you from observing nebulae and galaxies, but it could afford ideal seeing conditions for high power targets like double stars.

A Selection of Double Stars in Cancer

For our spring double star selection, we’ll say goodbye to Gemini and shift eastward to the faint constellation Cancer. Notable for its bright Messier cluster M44 (the Praesepe), Cancer is also home to a splendid array of double and multiple stars. How many can you notch? (Data from the Washington Double Star Catalog (WDS)

A Selection of Double Stars in Gemini

It’s appropriate that the constellation Gemini, the Twins, should be home to a numerous collection of double stars. Here are ten stellar – pardon the pun - examples (data from the Washington Double Star Catalog (WDS).

A Selection of Double Stars in Cygnus

Although it’s a Summer Triangle constellation, Cygnus remains well-seen throughout the autumn months. Located in the star-rich fields of the Milky Way, the Swan is home to numerous double stars. Here are eight of the most noteworthy (data from the Washington Double Star Catalog.

A Selection of Double Stars in Scorpius

Our summer double star adventure takes us to the southern skies and the constellation Scorpius. The region north and west of, and including, Antares contains a remarkable array of showpiece double and multiple stars.

A Selection of Double Stars in Corona Borealis

It’s time to come out of hibernation! After two months of intense cold weather here in the Northeast, mild temperatures are returning. Celebrate spring with a visit to one of the season’s loveliest constellations, Corona Borealis. The Northern Crown is home to a splendid collection of double stars. Here are ten of the most noteworthy.
A Selection of Double Stars in Boötes

A Selection of Double Stars in Boötes

During the warm summer evenings, the constellation Boötes is perched high in the sky after sunset. The Herdsman is a rich hunting ground for double stars.

Some Bright Spring Double Stars

To most deep sky enthusiasts, spring means “galaxies.” Hundreds of these island universes – many in the Coma-Virgo cluster – are within the reach of backyard scopes. Often forgotten are the beautiful double stars that also inhabit the spring skies. Here are ten of the best:

Some Bright Winter Double Stars

The winter night sky, dominated by mighty Orion, is rich with deep-sky splendors. If you can brave the cold, you’ll be rewarded by some of the finest double and triple stars the night sky has to offer.

Some Bright Autumn Double Stars

Autumn is a season of promise for the stargazers. The nights are getting longer, the air clearer, and those pesky summer mosquitoes are a thing of the past. In a few months, Orion and his magnificent wintry retinue will take center stage. While the autumn night sky appears devoid of bright stars, it’s still home to a rich array of double stars. Here are ten of the best:

Some Bright Summer Double Stars

In this modern era of the huge galaxy-gulping Dobsonian reflector, double stars have become the neglected children of the cosmos. That’s too bad, because few heavenly objects have the visual appeal of double stars.
  • Struve 817 Orionis