Messier 12 (M12) – The NGC 6118 Globular Cluster

The M12 globular cluster, image taken by the Hubble Space Telescope. Credit: NASA/Hubble Heritage Team /AURA/STScI

Welcome back to another edition of Messier Monday! Today, we continue in our tribute to Tammy Plotner with a look at the M12 globular cluster!

In the 18th century, French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky which he originally mistook for comets. After realizing his mistake, he began compiling a list of these objects in order to ensure that other astronomers did not make the same error. In time, this list would include 100 objects, and would come to be known as the Messier Catalog to posterity.

One the many objects included in this is Messier 12 (aka. M12 or NGC 6218), a globular cluster located in the Ophiuchus constellation some 15,700 light-years from Earth.  M12 is positioned just 3° from the cluster M10, and the two are among the brightest of the seven Messier globulars located in Ophiuchus. It is also interesting to note that M12 is approaching our Solar System at a velocity of 16 km/s.

Continue reading “Messier 12 (M12) – The NGC 6118 Globular Cluster”

Messier 11 (M11) – The Wild Duck Cluster

The Wild Duck Cluster photographed on amateur astrophotography equipment. Credit: Creative Commons/Rawastrodata

Welcome back to another edition of Messier Monday! Today, we continue in our tribute to Tammy Plotner with a look at the M11 Wild Duck Cluster!

In the 18th century, French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky while searching for comets. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of 1oo  of them. This list came to be known as the Messier Catalog, and would have far-reaching consequences.

One of these objects is M11, otherwise known as The Wild Duck Cluster, an open cluster located in the constellation Scutum, near the northern edge of a rich Milky Way star cloud (the Scutum Cloud). This open star cluster is one of the richest and most compact of all those known, composed of a few thousand hot, young stars that are only a few million years old.

Continue reading “Messier 11 (M11) – The Wild Duck Cluster”

Messier 10 (M10) – The NGC 6254 Globular Cluster

Messier Object 10. as imaged by the Hubble Space Telescope Credit: NASA/:STScI:WikiSky

Welcome to another installment of Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by taking a look at Messier Object 10.

In the 18th century, French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky while searching for comets. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of 1oo  of them. This list came to be known as the Messier Catalog, and would have far-reaching consequences.

In addition to being as a major milestone in the history of astronomy and the study of Deep Sky Objects. One of these objects is known as Messier 10 (aka. NGC 6254), a globular cluster that is located in the equatorial constellation of Ophiuchus. Of the many globular clusters that appear in this constellation (seven of which were cataloged by Messier himself) M10 is the brightest, and can be spotted with little more than a pair of binoculars. Continue reading “Messier 10 (M10) – The NGC 6254 Globular Cluster”

Messier 8 (M8) – The Lagoon Nebula

The Lagoon Nebula, as imaged by the VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile. Credit: ESO/VPHAS

Welcome to another Messier Monday. In our ongoing tribute to the great Tammy Plotner, we bring you another item from the Messier Catalog!

In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function, acting as a milestone in the history of the study of Deep Sky Objects.

However, not all objects in the catalog were first discovered by Charles Messier himself. Some, like the Lagoon Nebula, were observed sooner, owing to the fact that they are visible to the naked eye. This interstellar cloud, which is located in the Sagittarius constellation, has been known of since the late 17th century, and is one of only two star-forming nebulae that is visible to the naked eye from mid-northern latitudes.

Continue reading “Messier 8 (M8) – The Lagoon Nebula”

Messier 6 – The Butterfly Cluster

M6 open cluster (NGC 6405). Credit: Ole Nielsen

Welcome back to Messier Monday! We continue our tribute to our dear friend, Tammy Plotner, by looking at Messier 6, otherwise known as NGC 6405 and the Butterfly Cluster. Enjoy!

In the late 18th century, Charles Messier was busy hunting for comets in the night sky, and noticed several “nebulous” objects. After initially mistaking them for the comets he was seeking, he began to compile a list of these objects so other astronomers would not make the same mistake. Known as the Messier Catalog, this list consists of 100 objects, consisting of distant galaxies, nebulae, and star clusters.

This Catalog would go on to become a major milestone in the history of astronomy, as well as the study of Deep Sky Objects. Among the many famous objects in this catalog is M6 (aka. NGC 6405), an open cluster of stars in the constellation of Scorpius. Because of its vague resemblance to a butterfly, it is known as the Butterfly Cluster.

Continue reading “Messier 6 – The Butterfly Cluster”

Messier 5 (M5) – The NGC 5904 Globular Cluster

The globular cluster Messier 5, one of the oldest belonging to the Milky Way. Credit: NASA/ESA/HST

In the late 18th century, Charles Messier was busy hunting for comets in the night sky, and noticed several “nebulous” objects. After initially mistaking them for the comets he was seeking, he began to compile a list of these objects so other astronomers would not make the same mistake. Known as the Messier Catalog, this list consists of 100 objects, consisting of distant galaxies, nebulae, and star clusters.

Among the many famous objects in this catalog is the M5 globular star cluster (aka. NGC 5904). Located in the galactic halo within the Serpens Constellation, this cluster of stars is almost as old as the Universe itself (13 billion years)! Though very distant from Earth and hard to spot, it is a favorite amongst amateur astronomers who swear by its beauty.

Continue reading “Messier 5 (M5) – The NGC 5904 Globular Cluster”

Messier 4 (M4) – The NGC 6121 Globular Cluster

This M4 globular cluster, as imaged by the Wide Field Imager at ESO’s La Silla Observatory. Credit: ESO

During the late 18th century, Charles Messier began to notice that a series of “nebulous” objects in the night sky that he originally mistook for comets. In time, he would notice that they were in fact something significantly different. With the hope of preventing other astronomers from making the same mistake, he began compiling a list of these in what would come to be known as the Messier Catalog.

Consisting of 100 objects, the catalog became an important milestone in both astronomy and the research of Deep Sky objects. Among the many famous objects in this catalog is the M4 loose globular cluster (aka. NGC 6121). Located in the Scorpius (Scorpio) Constellation, this great cluster of ancient stars is one of the closest Messier Objects of its kind to Earth.

Continue reading “Messier 4 (M4) – The NGC 6121 Globular Cluster”

Messier 1 (M1) – The Crab Nebula

The Crab Nebula (aka. Messier Object 1) is an example of a supernova explosion that emitted cosmic rays. Credit: NASA

In the 18th century, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. Initially, he thought these were comets, which he was attempting to locate at the time. However, astronomers would later discover that these objects were in fact nebulae, galaxies and star clusters. Between the years of 1758 and 1782, Messier compiled a list of approximately 100 of these objects.

His intention was to ensure that other astronomers would not mistake these objects for comets. But in time, this list – known as the Messier Catalog – served a higher purpose. In addition to being a collection of some of the most beautiful objects in the night sky, the catalog was also an important milestone in the discovery and research of Deep Sky objects. The first item in the catalog is the famous Crab Nebula – hence its designation as Messier Object 1, or M1.

Description:

Messier 1 (aka. M1, NGC 1952, Sharpless 244, and the Crab Nebula) is a supernova remnant located in the Perseus Arm of the Milky Way Galaxy, roughly 6500 ± 1600 light years from Earth. Like all supernova remnants, it is an expanding cloud of gas that was created during the explosion of a star. This material is spread over a volume approximately 13 ± 3 ly in diameter, and is still expanding at a velocity of about 1,500 km/s (930 mi/s).

Based on its current rate of expansion, it is assumed that the overall deceleration of the nebula’s expansion must has decreased since the initial supernova. Essentially, after the explosion occurred, the nebula’s pulsar would have began to emit radiation that fed the nebula’s magnetic field, thus expanding it and forcing it outward.

The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image.
The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer.

In visible light, the Crab Nebula consists of an oval-shaped mass of filaments – whose spectral emission lines are split into both red and blue-shifted components – which surround a blue central region. The filament are leftover from the outer layers of the former star’s atmosphere, and consist primarily of hydrogen and helium, along with traces of carbon, oxygen, nitrogen and heavier elements. The filaments’ temperatures are typically between 11,000 and 18,000 K.

The blue region, meanwhile, is the result of highly polarized synchrotron radiation, which is emitted by high-energy electrons in a strong magnetic field. The curved path of these electrons is due to the strong magnetic field produced by the neutron star at the center of the nebula (see below). One of the many components of the Crab Nebula is a helium-rich torus which is visible as an east-west band crossing the pulsar region.

The torus accounts for about 25% of the nebula’s visible ejecta and is believed to be made up of 95% helium. As yet, there has been no plausible explanation for the structure of the torus. And while it is very difficult to gauge the total mass of the nebula, official estimates place it at 4.6 ± 1.8 Solar masses – i.e 5.5664 to 12.7232 × 1030 kg.

Crab Pulsar:

At the center of the Crab Nebula are two faint stars, one of which is its progenitor (i.e the one that created it). It is because of this star that M1 is a strong source of radio waves, X-rays and Gamma-ray radiation. The remnant of supernova SN 1054, which was widely observed on Earth in the year 1054, this star was discovered in 1968 and has since been designated as a radio pulsar.

The Crab Nebula Pulsar, M1. Both are sequences of observations that show the expansion of shock waves emanating from the Pulsar interacting with the surrounding nebula. The Crab Pulsar actually pulsates 30 times per second a result of its rotation rate and the relative offset of the magnetic pole. Charndra X-Rays (left), Hubble Visible light (right). (Credit: NASA, JPL-Caltech)
Observation sequences of M1, showing the expansion of shock waves emanating from the Pulsar interacting with the surrounding nebula.  Charndra X-Rays (left), Hubble Visible light (right). (Credit: NASA, JPL-Caltech)

Known as the Crab Pulsar (or NP0532), this rapidly rotating star is believed to be about 28–30 km (17–19 mi) in diameter and emits pulses of radiation – ranging from radio wave and X-ray  – every 33 milliseconds. Like all isolated pulsars, its period is slowing very gradually, and the energy released as the pulsar slows down is enormous. The Crab Pulsar is also the source of the nebula’s synchrotron radiation, which has a total luminosity about 75,000 times greater than that of the Sun.

The pulsar’s extreme energy output also creates an unusually dynamic region at the center of the Crab Nebula. While most astronomical objects only show changes over timescales of many years, the inner parts of the Crab show changes over the course of only a few days. The most dynamic feature in the inner part of the nebula is the point where the pulsar’s equatorial wind slams into the bulk of the nebula, forming a shock front (see above image).

The Crab Pulsar is also surrounded by an expanding gas shell which encompasses its spectroscopic companion star, which in turn orbits the neutron star every 133 days. This pulsar was the first one which was also verified in the optical part of the spectrum.

History of Observation:

The very first recorded information on this supernova event reaches as far back as July 4, 1054 A.D. by Chinese astronomers who marked the presence of a “new star” visible in daylight for 23 days and 653 nights. The event may have also been recorded by the Anasazi, Navajo and Mimbres First Nations of North America in their artwork as well.

Charles Messier, French astronomer, at the age of 40, by Ansiaume. Credit: Public Domain.
Charles Messier, French astronomer, at the age of 40, by Nicolas Ansiaume. Credit: Public Domain.

In more modern times, the nebula was cataloged as a discovery by British amateur astronomer John Bevis in 1731, and independently by Charles Messier on August 28th, 1758 while looking for the return of Comet Halley. Although Bevis had added it to his “Uranographia Britannica”, Messier recognized what he had located had no proper motion, and was therefore not a comet. However, Messier did credit Bevis’ discovery when he learned of it years later.

By September 12th, 1758, Messier hit upon the idea of compiling a catalog of objects that weren’t comets, in order to help other astronomers avoid similar mistakes. Considering M1’s position, only slightly more than a degree from the ecliptic plane, this was a very good idea. Especially since M1 was again confused with Halley’s Comet when it returned in 1835.

The name Crab Nebula was first suggested by William Parsons, the Third Earl of Rosse, who observed it while at Birr Castle in 1884. The name was apparently due to the drawing he made of it, which resembled a crab. When he observed it again in 1848 using a ]telescope with better resolution, he could not confirm the resemblance. But the name had become popular by this point and has stuck ever since.

Our eyes would never see the Crab Nebula or Messier 1 as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
Our eyes would never see the Crab Nebula as this Hubble image shows it. Credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

All of the early observers – including Herschel, Bode, Messier and Lassell – apparently mistook the filamentary structures of the Nebula as an  indication of stellar structure. As Messier himself described it:

“Nebula above the southern horn of Taurus, it doesn’t contain any star; it is a whitish light, elongated in the shape of a flame of a candle, discovered while observing the comet of 1758. See the chart of that comet, Mem. Acad. of the year 1759, page 188; observed by Dr. Bevis in about 1731. It is reported on the English Celestial Atlas.”

Sir Williams Herschel’s writing on the nebula appeared in the 74th volume of the Philosophical Transactions of the Royal Society of London, which was released in 1784. As he described it:

“To these may added the 1st [M1], 3d, 27, 33, 57, 79, 81, 82, 101 [of Messier’s catalog], which in my 7, 10, and 20-feet reflectors shewed a mottled kind of nebulosity, which I shall call resolvable; so that I expect my present telescope will, perhaps, render the stars visible of which I suppose them to be composed…”

Reproduction of the first depiction of the Messier 1 nebula by Lord Rosse (1844) (colour-inverted to appear white-on-black) William Parsons, 3rd Earl of Rosse - http://messier.seds.org/more/m001_rosse.html
Reproduction of the first depiction of the nebula by Lord Rosse (1844). Credit: messier.seds.org

But it was Parsons (aka. Lord Rosse) who first recognized M1 for what we know it as today. As he recorded when viewing it for the first time (in 1844):

“Fig. 81 is also a cluster; we perceive in this [36-inch telescope], however, a considerable change of appearance; it is no longer an oval resolvable [mottled] Nebula; we see resolvable filaments singularly disposed, springing principally from its southern extremity, and not, as is usual in clusters, irregularly in all directions. Probably greater power would bring out other filaments, and it would then assume the ordinary form of a cluster. It is stubbed with stars, mixed however with a nebulosity probably consisting of stars too minute to be recognized. It is an easy object, and I have shown it to many, and all have been at once struck with its remarkable aspect. Everything in the sketch can be seen under moderately favourable circumstances.”

Locating Messier 1:

The Crab Nebula is easily visible in the night sky near the Taurus constellation, whenever light pollution is not an issue. It can be located by identifying Zeta Tauri, a third magnitude star located east/northeast of Aldebaran. With dark sky conditions, it can be seen as a tiny, hazy patch with binoculars and small telescopes with low magnification. If sky conditions are bright, it may be harder to locate with modest equipment.

The constellation Taurus. Credit: iau.org
Messier Object 1 sits between the Taurus, Orion, and Auriga constellations. Credit: iau.org

With a little more magnification, it is seen as a nebulous oval patch, surrounded by haze. In telescopes starting with 4-inch aperture, some detail in its shape becomes apparent, with some suggestion of mottled or streak structure in the inner part of the nebula. To the amateur astronomer, M1 does indeed look similar to a faint comet without a tail.

As Messier 1 is situated only 1 1/2 degrees from the ecliptic, there are frequent conjunctions and occasional transits of planets, as well as occultations by the Moon. And for the sake of simplicity, here are the vital statistics on this Messier Object:

Object Name: Messier 1
Alternative Designations: NGC 1952, M1, Sharpless 244, Crab Nebula
Object Type: Supernova Remnant
Constellation: Taurus
Right Ascension: 05 : 34.5 (h:m)
Declination: +22 : 01 (deg:m)
Distance: 6.3 (kly)
Visual Brightness: 8.4 (mag)
Apparent Dimension: 6×4 (arc min)

We wish you luck in locating it in the night sky. And should you find it, enjoy your observations!

We have written many great articles about the Crab Nebula and Messier Objects here at Universe Today. Here’s What Is The Crab Nebula?, The Peculiar Pulsar in the Crab Nebula, and Top Five Celestial Objects Anyone Can See With A Small Telescope.

Be sure to check out our complete Messier Catalog.

For more information, check out the SEDS Messier Database.

Ready, Set, Messier Marathon: A 2014 Guide

Patiently awaiting darkness at the starting line... Credit and copyright: John Chumack.

Have YOU seen all 110?

The passage of the northward equinox last week on March 20th means one thing in the minds of many a backyard observer: the start of Messier Marathon season. This is a time of year during which a dedicated observer can conceivably spot all of the objects in Charles Messier’s famous deep sky catalog in the span of one night.

We’ve written about some tips and tricks to completing this challenge previously, as well as the optimal dates for carrying a marathon out. Typically, the New Moon weekend nearest the March equinox is the best time of year for northern hemisphere observers to target all of the objects on Messier’s list. This works because a majority of the Messier objects are clustered into two regions: towards the core of our galaxy in Sagittarius — where the Sun sits during the December solstice — up through the summer triangle constellations of Cygnus, Aquila and Lyra, and in the bowl of Virgo asterism and its super cluster of galaxies that extends northward into the constellation of Coma Berenices. In March through early April the Sun sits in the constellation of Pisces, well away from the galactic plane.

The prospects for completing a Messier marathon in 2014 favor the last weekend on March on the 29th-30th. The Moon reaches New on Sunday, March 30th at 18:45 Universal Time/2:45 PM EDT.

Messier marathons first came into vogue in the early 1970s right around the time Schmidt-Cassegrain and large Dobsonian “light bucket” telescopes came into general use.

Charles Messier began noting the curious objects that he would later incorporate into his famous catalog during the summer of 1758, with his description of the Crab Nebula in Taurus, which would become Messier object number one or M1. Messier was a prolific comet hunter and discovered 21 comets in his lifetime. The catalog was compiled over the span of 13 years from 1771 to 1784. Messier’s original list contained 45 objects, and was later expanded in subsequent editions 103, with Messier’s assistant Pierre Méchain adding six more objects to the catalog. The list is generally tallied at 110 objects, with one famous controversy being M102, which is generally cited as a re-observation of M101 or the galaxy NGC 5866.

The catalog itself contains a grab bag of open and globular clusters, galaxies, planetary and diffuse nebulae, and one double star (M40). The Messier catalog spans the sky down to M7, an object also known as the Ptolemy Cluster, which is the southernmost object on the list at latitude -34 degrees 48’ south.

The first page of Messier's third revision of his catalog describing M1 through M5. Image in th Public Domain.
The first page of Messier’s third revision of his catalog, describing M1 through M5. Image in the Public Domain.

Messier observed from Paris at latitude +48 degrees 51’ north using two primary telescopes of the almost one dozen that he owned for his discoveries: a 6.4” Gregorian reflector and a 3.5” refractor. Messier knew nothing of the nature of these “faint fuzzies” that he’d periodically stumbled across in his cometary vigil. His original intent was to compile a list of “comet imposters” in the night sky for comet hunters to be aware of in their quests. In his words:

“What made me produce this catalog was the nebula which I had seen in Taurus while I was observing the comet of that year (1758). The shape and brightness of that nebula reminded me so much of a comet, that I undertook to find more of its kind, to save astronomers from confusing these nebulae with comets.”

“Beware, here doth not lie comets,” Messier admonishes future generations of observers. Still, some peculiarities remain in the catalog: why did Messier, for example, include such obvious “non-comets” as the Pleiades (M45), but skip over the brilliant Double Cluster in Perseus?

Charles Messier's 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain.
Charles Messier’s 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain.

Alas, such mysteries are known only to Messier, who was interred at the famous Père Lachaise cemetery after his death in 1817. When we visit Paris, we’ll bypass Jim Morison to leave a copy of Burnham’s Celestial Handbook at Messier’s grave.

And just like the road variety, “running the Messier marathon” takes all of the stamina and pacing that a visual athlete can muster. You’ll want to grab M77 and M74 immediately after dusk, or the marathon will be over before it starts. From there, move on up north to the famous Andromeda galaxy (M31) and the scattering of objects around it before settling in for a more leisurely observing pace moving westward through the constellations of Orion, Leo and surrounding objects.

An all-sky map showing the distribution of Messier objects. (Click to enlarge). Credit: Jim Cornmell under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license.
An all-sky map showing the distribution of Messier objects. (Click to enlarge). Credit: Jim Cornmell under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license.

Now towards the approach of local midnight comes the first large group: the Virgo cluster of galaxies extending through Coma Berenices, rising to the east. After this batch, you can catch some quick shut-eye before bagging the Messier objects towards the galactic center and up through Cygnus in the pre-dawn. Plan ahead; M52, M2 and M30 are especially notoriously difficult in the spring dawn sky!

It’s also worth noting your “attitude versus latitude” plays a role as well. To this end, Ed Kotapish compiled this nifty perpetual chart of when the entire Messier catalog is visible from respective latitudes:

A chart calculating number of total Messier objects that are visible on the dates (vertical column in month-day format) versus north latitude (top row). Note that this chart is pertpetual for non-leap years, and does not take into account the pahse of the Moon. Click to enlarge. Credit: Edward Kotapish.
A chart calculating number of total Messier objects that are visible on the dates (vertical column in month-day format) versus north latitude (top row). Note that this chart is pertpetual for non-leap years, and does not take into account the pahse of the Moon. Click to enlarge. Credit: Edward Kotapish.

“The bounds of the chart are for a variety of objects,” Ed told Universe Today. “I used nautical twilight (when the Sun falls below -12 degrees in elevation) as the starting and ending condition.” Ed also notes that the top curve of the chart on the morning side is bounded by the difficulty in finding troublesome M30, while the left bottom evening boundary is limited by the observability of M110 and M74, which can be a problem for observers at higher latitudes.

Alternate versions of the Messier marathon exist as well, such as imaging or even sketching all 110 objects in one night.

Why complete a Messier marathon? Well, not only does such a feat hone your visual skills as an observer, but it also familiarizes you with the entire catalog… and there’s nothing that says you have to complete it all in one evening, except of course, for bragging rights at the next star party!

Good luck!

-Here’s a handy list of all 110 of the Messier objects in the catalog.

-Be sure to send those pics of Messier objects and more in to Universe Today’s Flickr forum!

Why This Weekend is Perfect for a Messier Marathon

To 'scopes, get set, marathon! (A homemade 14" Gregorian reflector, photo by author).

This coming weekend presents the first window for 2013 to complete a challenge in the realm of backyard astronomy and visual athletics. With some careful planning, persistence, and just plain luck, you can join the vaunted ranks of those seasoned observers who’ve seen all 110 objects in the Messier catalog… in one night.

Observing all of the objects in Messier’s catalog in a single night has become a bit of a sport over the last few decades for northern hemisphere observers, and several clubs and organizations now offer certificates for the same.  The catalog itself was a first attempt by French astronomer Charles Messier to catalog the menagerie of “faint fuzzies” strewn about the northern hemisphere sky.

Not that Charles knew much about the nature of what he was seeing. The modern Messier catalog includes a grab bag collection of galaxies, nebulae, open and globular clusters and more down to magnitude +11.5, all above declination -35°. Charles carried out his observations from Paris France at latitude +49° north. Unfortunately, this  also means that Messier catalog is the product of Charles Messier’s northern-based vantage point. The northernmost objects in the catalog are Messiers 81 & 82 at declination +69°, which never get above the horizon for observers south of latitude -21°. His initial publication of the catalog in 1774 contained 45 objects, and his final publication contained 103, with more objects added based on his notes after his death in 1817. (Fun fact: Messier is buried in the famous Père Lachaise Cemetery in Paris, site of other notable graves such as those of Chopin and Jim Morrison).

M51, the Whirlpool Galaxy, one of the more photogenic objects in the Messier catalog. (Credit: NASA/Hubble Heritage Project).
M51, the Whirlpool Galaxy, one of the more photogenic objects in the Messier catalog. (Credit: NASA/Hubble Heritage Project).

There’s a fair amount of controversy on Messier’s motivations and methods for compiling his catalog. The standard mantra that will probably always be with us is that Messier was frustrated with stumbling across these objects in his hunt for comets and decided to catalog them once and for all. He eventually discovered 13 comets in his lifetime, including Comet Lexell which passed only 2.2 million kilometres from Earth in 1770.

No one is certain where the modern tradition of the Messier Marathon arose, though it most likely had its roots in the amateur astronomy boom of the 1970s and was a fixture of many astronomy clubs by the 1980s. There are no Messier objects located between right ascension 21 hours 40 minutes  and 23 hours 20 minutes, and only one (M52)  between 23 hours 20 minutes and 0 hours 40 minutes. With the Sun reaching the “0 hour” equinoctial point on the March Vernal Equinox (falling on March 20th as reckoned in Universal Time for the next decade), all of the Messier objects are theoretically observable in one night around early March to early April. Taking into account for the New Moon nearest to the March equinox, the best dates for a weekend Messier marathon for the remainder of the decade are as follows;

Optimal Messier marathon dates for the remainder of the decade. (Compiled by author).
Optimal Messier marathon dates for the remainder of the decade. (Compiled by author).

Note that this year’s weekend is very nearly the earliest that it can occur. The optimal latitude for Messier marathoning is usually quoted as 25° north, about the latitude of Miami. It’s worth noting that 2013 is one of the very few years where the primary weekend falls on or before our shift one hour forward to Daylight Saving time, occurring this year on March 10th for North America.

Students of the Messier catalog will also know of the several controversies that exist within the list. For example, one wide double star in Ursa Major made its way into the catalog as Messier 40. There’s also been debate over the years as to the true identity of Messier 102, and most marathoners accept the galaxy NGC 5866 in its stead. Optics of the day weren’t the most stellar (bad pun intended) and this is evident in the inclusion of some objects but the omission of others. For example, it’s hard to imagine a would-be comet hunter mistaking the Pleiades (M45) for an icy interloper, but curiously, Messier omits the brilliant Double Cluster in Perseus.

M42, the Orion Nebula. (Photo by Author, taken back in the days of ye ole film!)
M42, the Orion Nebula. (Photo by Author, taken back in the days of ye ole film!)

It’s vital for Messier marathoners to run through objects in proper sequence. Most visual observers run these in groups, although Alex McConahay suggests in a recent April 2013 Sky & Telescope article that folks running a photographic marathon (see below) beware of wasting precious time crossing the celestial meridian (a maneuver which requires a telescope equipped with a German Equatorial mount to “flip” sides) hunting down objects. The unspoken “code of the skies” for visual Messier marathoners is that “Go-To” equipped scopes are forbidden. Part of the intended purpose of the exercise is to acquaint you with the night sky via star hopping to the target.

Most observers complete Messier objects in groups. You’ll want to nab M77 and M74 immediately after local dusk, or the marathon will be over before it starts. You’ll then want to move over to the Andromeda Galaxy and the collection of objects in its vicinity before scouring Orion and environs. From that point out, you can begin to slow down a bit and pace yourself through the galaxy groups in Coma Berenices and the Bowl of Virgo asterism. Another cluster of objects stretch out in the sky past midnight along the plane of our Milky Way Galaxy from Sagittarius to Cygnus, and the final (and often most troublesome) targets to bag are the Messier objects in Aquarius and M30 in Capricornus just before dawn. Remember, dark skies, warm clothes, and hot coffee are your friends in this endeavor!

There have been alternate rules or versions of Messier marathons over the years. Some imagers complete one-night photographic messier marathons. There are even abbreviated or expanded versions of the feat. It is also possible to nab most of the Messier catalog with a good pair of binoculars under clear skies. Probably the most challenging version we’ve heard of is sketching all 110 Messier objects in one evening… you might be forgiven for using a Go-To enabled telescope to accomplish this!

Finally, just like running marathons, the question we often get is why. Some may eschew transforming the art of dark sky observing into a task of visual gymnastics. We feel that to run through this most famous of catalogs in an evening is a great way to learn the sky and practice the fast-disappearing art of star hopping. And hey, no one’s saying you can’t take a year or three to finish the Messier catalog… its a big universe, and the New General Catalog (NGC) and Index Catalog (IC) containing thousands of objects will still be waiting. Have YOU seen all 110?

–      A perpetual listing of Messier marathon visibility by latitude by Tom Polakis.

–      An All Sky Map of the Messier catalog.

–      A handy priority list for a Messier marathon compiled by Don Machholz.