Upstate New York Stargazing – March, 2017

Author's Note: The "Upstate New York Stargazing" series ran on the and websites (and limited use in-print) from 2016 to 2018. For the full list of articles, see the Upstate New York Stargazing page.

Upstate NY Stargazing In March: Messier Marathon and the Lunar Occultation of Aldebaran

M31, the Andromeda Galaxy, and its satellite galaxies M32 (a hazy star just above-left of M31's center) and M110 (the oval structure below-left of M31's center). Photograph taken at Kopernik Observatory & Science Center by Kopernik Astronomical Society member George Normandin. Click for a larger view.

Updated: Feb. 28, 2017, 5:12 p.m. | Published: Feb. 28, 2017, 4:12 p.m.

Special to

By Damian Allis | Contributing writer

When someone refers to an astronomical object as "M" and a number, just what do they mean?

Once upon a time in astronomy, we didn't much know anything. Our classification throughout most of human history divided the nighttime sky into (1) pinpoints of light that didn't move with respect to each other (stars), (2) points of light that did move (planets), (3) random streaks of light that moved very quickly and disappeared (meteors), (4) the very rare pinpoints of light that grew bright and then disappeared completely (nova, supernova) and (5) the Moon.

There was also a rare sixth kind of object – comets. Comets grew bright over time before disappearing again, moved with respect to the backdrop of stars, looked like a hazy ball of light instead of a sharp pinpoint, and some were even known to come back around our way every certain number of years – a true hybrid of properties. Perhaps the most famous comet is the 75-ish year period Halley's Comet. Literary buffs will know that Mark Twain was born in 1835, the year of a Halley fly-by, and died in 1909, the year of the next Halley pass. He was even quoted as saying "It will be the greatest disappointment of my life if I don't go out with Halley's Comet."

European history buffs may know that the 1066 fly-by of Halley's Comet was seen as an omen – albeit an eventually poor one for Harold II of England, who suffered death and defeat at the swords and stirrups of William the Conqueror at the Battle of Hastings. The Bayeux Tapestry, which records the events leading up to this famed battle, even includes the sighting of the at-that-time-unnamed Halley's Comet.

Now we zoom in on the "M" – as it happens, many deep sky objects, including globular star clusters, galaxies, and nebulae, can look a bit comet-ish when magnified. This is especially true in poor quality equipment, where bad optics make everything unresolvable, adding a hazy glow to further confuse the issue. The "street cred" that came with the discovery of and naming rights for comets instigated many to push the limits of scope building and observing after Galileo's first foray into telescope observing, as better optics and higher magnification meant catching sight sooner than anyone else. Fortunately for methodical comet hunters, many of the hazy deep sky objects in their sights did not move in the sky with respect to the stars around them – meaning, to borrow from another space adventure, "these aren't the comets you're looking for."

Enter the "M" – Charles Messier, the famed French comet hunter whose observing prowess gave him a near-monopoly on comet discoveries between 1760 and 1785. In an effort to keep track of stationary stellar fuzz balls, and to pre-empt the erroneous reporting of new comets by others, Messier marked the locations of 17 comet-like objects in the sky that did not move, added 28 other fixed objects discovered previously, and published all 45 in 1774 in what became the first Messier Catalogue. The final catalogue published by Messier and his assistant Pierre Mechain in 1781 included 103 objects. The list was further expanded to 110 by later astronomers who saw evidence for the observations of M104 to M110 in M+M's observing logs, with M110 added just in 1967. The Messier Catalogue accounts for nearly all of the deep sky objects you can see with a decent pair of binoculars in the Northern Hemisphere.

For those keeping track, the irony of the whole situation is that Messier, famed comet hunter, is remembered for making a catalogue of those things which are, in fact, not comets.

All 110 Messier Objects – and most will not look this good in your binoculars Click for a larger view.

The entire Messier Catalogue, spread throughout the sky as it is, can be observed in its entirety under clear, dark skies very near the New Moon between mid-March and early April. Amateur astronomers the world over engage in what is known as the "Messier Marathon," one of the great yearly tests of an observer's equipment, eyesight, and patience. You have to start *very* soon after sunset to catch the earliest setters, then can enjoy a more leisurely tour of the nighttime sky, sneaking in an occasional nap or big cup of coffee before catching the last few objects *very* soon before sunrise. These marathons are not easy! Observers with several years of experience may have trouble seeing the dimmest members of the list, but even new observers with good binoculars and simple star charts can find the brightest members of the catalogue in what are often called "Messier Sprints." A web search for "Messier Marathon" will provide numerous useful links, including maps to these objects, recording logs for each object, and even the most efficient search order to find and record your observations.

March lectures and observing opportunities

New York has a number of evenly-spaced astronomers, astronomy clubs, and observatories that host public sessions throughout the year. Many of these sessions are close to the New Moon, when skies are darkest and the chances for seeing deep, distant objects are best. These observers and facilities are the very best places to see the month's best objects using some of the best equipment, all while having very knowledgeable observers at your side to answer questions and guide discussion. Many of these organizations also hold monthly meetings, where seasoned amateurs can learn about recent discoveries from guest lecturers, and brand new observers are encouraged to join and begin the path towards seasoned amateur status.

Announced public sessions from several respondent NY astronomy organizations are provided below for March. As wind and cloud cover are always factors when observing, please check the provided contact information and/or email the groups a day-or-so before an announced session. Also use the contact info for directions and to check on any applicable event or parking fees, Some groups will schedule weather-alternate dates for some sessions.

Astronomy Events Calendar

OrganizerLocationEventDateTimeContact Info
Adirondack Public ObservatoryTupper LakePublic Star GazingMar. 36:00 PMemail, website
Adirondack Public ObservatoryTupper LakePublic Star GazingMar. 176:00 PMemail, website
Albany Area Amateur Astronomers & Dudley ObservatorySchenectadySenior Science DayMar. 63:00 – 4:00 PMemail, website
Albany Area Amateur Astronomers & Dudley ObservatorySchenectadyAAAA MeetingsMar. 167:30 – 9:00 PMemail, website
Albany Area Amateur Astronomers & Dudley ObservatorySchenectadyNight Sky AdventureMar. 217:00 – 8:30 PMemail, website
Astronomy Section, Rochester Academy of ScienceRochesterASRAS Meeting And LectureMar. 37:30 – 9:30 PMemail, website
Astronomy Section, Rochester Academy of ScienceRochesterTelescope Tune-Up @ StrasenburghMar. 1811:00 AM – 4:00 PMemail, website
Baltimore WoodsMarcellusGoodbye To Winter SkiesMar. 37:00 – 9:00 PMemail, website
Baltimore WoodsMarcellusMercury, Jupiter, Spring SkiesMar. 316:00 – 9:00 PMemail, website
Kopernik Observatory & Science CenterVestalMonthly MeetingMar. 17:00 – 9:00 PMemail, website
Kopernik Observatory & Science CenterVestalFriday Night ObservingMar. 37:30 PMemail, website
Kopernik Observatory & Science CenterVestalFriday Night ObservingMar. 107:30 PMemail, website
Kopernik Observatory & Science CenterVestalFriday Night ObservingMar. 177:30 PMemail, website
Kopernik Observatory & Science CenterVestalFriday Night ObservingMar. 247:30 PMemail, website
Kopernik Observatory & Science CenterVestalFriday Night ObservingMar. 317:30 PMemail, website
Mohawk Valley Astronomical SocietyWatervilleLecture: Math And The UniverseMar. 87:30 PMemail, website

For those still smitten with the NASA discovery of seven Earth-sized planets around TRAPPIST-1, attendees in the Cazenovia area are invited to the free lecture "Distant Worlds: What We Know About Extra-Solar Planets And Their Potential For Habitability" on March 1st in Hubbard Hall at Cazenovia College, given by Dr. Leslie Hebb from Hobart and William Smith Colleges and co-sponsored by the Cazenovia College Science Cafe Committee and CNY Observers. For additional information, please send an email to

Lunar Phases

New:First Quarter:Full:Third Quarter:New:
Feb. 26, 9:58 AMMar. 5, 6:32 AMMar. 12, 10:53 AMMar. 20, 11:58 AMMar. 27, 10:57 PM

The Moon's increasing brightness as Full Moon approaches washes out fainter stars, random meteors, and other celestial objects – this is bad for most observing, but excellent for new observers, as only the brightest stars (those that mark the major constellations) and planets remain visible for your easy identification. If you've never tried it, the Moon is a wonderful binocular object.

The grazing lunar occultation of Aldebaran. Click for a larger view.

Observers throughout Central and Southern New York are in for an observational treat on the evening of March 4th, when the Moon will occult the bright star Aldebaran, bright eye of the constellation Taurus the Bull. While the Moon occults, or blocks the light from, various stars and occasional planets all the time, the Aldebaran occultation is noteworthy because many observers will see Aldebaran just graze the Moon's edge. The luckiest observers may even see Aldebaran blink several times over the course of the occultation – this is huge! With no atmosphere to speak of, the blinking of Aldebaran you might see is, in fact, the star slipping behind large lunar geological features, such as high hills and the walls of impact craters. With enough observers and enough recorded data, astronomers can even make an elevation map of the grazed region of the Moon.

For those interested in all of the details, including the best ways to observe the event and how you can record data yourself for submission to the International Occultation Timing Association (IOTA), check out their official website.

Evening And Nighttime Guide

Items and events listed below assume you're outside and observing most anywhere in New York state. The longer you're outside and away from indoor or bright lights, the better your dark adaption will be. If you have to use your smartphone, find a red light app or piece of red acetate, else set your brightness as low as possible.

The view looking southwest at 9 p.m. on March 15 (except for the changing Moon position, this mid-month view is accurate for all of March). Click for a larger view.

Southern Sights: Orion, Taurus, and Canis Major are now primed for nighttime observing. High above them lies the twins Gemini – two very bright stars above Betelgeuse, the bright shoulder of Orion, will help orient you to find the stars that make up their bodies. These real beauties of winter skies will be nearly gone by the end of April, after which observers will have to wake up very early in August to see them again.

The view looking north at 9 p.m. on March 15. The Big Dipper is marked in green, including an arrow guide to finding Polaris, the North Star. Click for a larger view.

Northern Sights: Observers out during the late-evening hours are treated to a prominent Big Dipper standing upright in the northeastern sky and a prominent "E" shape in the northwest – the constellation Cassiopeia. The ancient king Cepheus sits near the horizon before midnight, looking like a dilapidated old barn. Once you've found the Big Dipper, take the two stars at the end of the bowl and guide your way to a moderately bright star surrounded by a mostly empty, dark piece of sky – this is the north star and tip of the Little Dipper handle, Polaris.

Planetary Viewing

Mercury starts the night above Venus on the 20th with Mars and a dim Uranus to the south. Click for a larger view.

Mercury: Mercury will be a bright pinpoint of light that will appear and then set just after sunset on March 11th. For the rest of the month, Mercury rises higher and sets later each night, falling behind Venus on the 20th and rising still higher in the sky through the end of March and early April. The 20th also offers a perfect time to catch four planets – Mars, Uranus, Mercury, and Venus – in the same part of the sky. On March 31, Mercury sets just after 9 p.m. EDT after crossing the Pisces-Aries border.

Venus on March 1st, off to the north of a tight grouping of the Moon, Mars, and Uranus. Click for a larger view.

Venus: Everyone's favorite misidentified UFO is going to zip along rather quickly from our view and through Pisces this month. Venus will set close to 8:30 p.m. on March 1st, a good 40 minutes or more before the crescent Moon and Mars do. On March 19th, Venus will set just after Mercury, newly arrived to the early-evening skies. On March 25th, Venus will set with the Sun and won't return to our evening skies until January of 2018. That said, Venus goes from being a bright evening object to a bright morning object instead! Between the 23rd and 25th, you have a decent chance of seeing Venus at sunset and at sunrise, after which Venus increasingly becomes a pre-dawn observing target until well into December of this year.

Mars: Mars will pair with the Moon this month in Pisces on March 1st and, once again, these two objects can guide you to finding the second-farthest planet in the Solar System. With luck and decent magnification, Uranus will appear as a green/blue point of light below Mars. If the Moon is too bright for easy scanning, simply wait until after the 1st for the Moon to make a little distance from Mars before trying for Uranus again. Mars will set very close to 9:20 p.m. EST / 10:20 EDT the entire month thanks to our mutual motions around the Sun, crossing the border from Pisces to Aries on March 8.

Jupiter and Moon close to Spica in Virgo on March 14. Click for a larger view.

Jupiter: March marks the triumphant return of Jupiter to our late-evening and early nighttime skies. On March 1, Jupiter rises in Virgo just after 9:30 p.m. By March 31, Jupiter will just hit the eastern tree line around 8:30 p.m. EDT.  Low power binoculars are excellent for spying the four bright Galilean moons – Io, Europa, Ganymede, and Callisto – and you are welcome to reproduce Galileo's observations of their motions around Jupiter. In fact, your generic, big-box store binoculars are a significant improvement over the equipment Galileo had at his disposal when he first began observing the heavens, so your task is all the easier. Several online guides will even map their orbits for you so you can identify their motions nightly or, for the patient observer, even hourly. The near-full Moon and Jupiter will make for a bright grouping with the bright Virgo star Spica in 10×50 binoculars after 10 p.m. EDT on March 14.

Saturn and the Moon on March 20th. Click for a larger view.

Saturn: Saturn continues it slow movement through Sagittarius this month, rising over the southeastern horizon just after 2:15 a.m. on March 1 and around 1:15 a.m. on the 31st. Saturn and the waning crescent Moon make for a close pair on March 20. Messier 23 will make for a small triangle in binoculars. The nebulae M21 and M20 can even be placed within the binocular field of view this night, but they will be very difficult to identify due to the brightness of the Moon.

ISS And Other Bright Flyovers

Satellite flyovers are commonplace, with several bright passes easily visible per hour in the nighttime sky, yet a thrill to new observers of all ages. Few flyovers compare in brightness or interest to the International Space Station. The flyovers of the football field-sized craft with its massive solar panel arrays can be predicted to within several seconds and take several minutes to complete.

The ISS is going to be an morning object until near the end of March. All of the morning sessions, from the 1st to the 23rd, fall into a window between 4:45 a.m. and 6:45 a.m., including double flyovers on the 18th, 20th, and 22nd. The "extremely" bright flyovers will be just that, with several expected to out-compete our late-evening Venus. At the end of the month, the ISS returns to the early evening, including double flyovers on the 29th and 31st. Simply go out a few minutes before the start time, orient yourself, and look for what will at first seem like a distant plane.

ISS fly-bys

DateBrightnessApprox. StartStart DirectionApprox. EndEnd Direction
3/1moderately6:05 AMS/SW6:11 AME/NE
3/3extremely5:56 AMSW6:03 AME/NE
3/4very5:05 AMS/SW5:10 AME/NE
3/5extremely5:48 AMW/SW5:54 AMNE
3/6extremely4:57 AMSW5:01 AME/NE
3/7very5:39 AMW5:45 AMNE
3/8extremely4:49 AMN/NW4:52 AMNE
3/9moderately5:31 AMW/NW5:36 AMNE
3/10moderately4:40 AMN/NW4:43 AMNE
3/11somewhat5:22 AMNW5:27 AMNE
3/12somewhat5:32 AMN5:34 AMNE
3/13somewhat6:13 AMNW6:18 AMNE
3/14somewhat5:23 AMN5:25 AMNE
3/15somewhat6:05 AMNW6:10 AME/NE
3/16somewhat5:14 AMN5:17 AMNE
3/17moderately5:56 AMNW6:01 AME
3/18extremely6:39 AMNW6:45 AME/SE
3/18somewhat5:05 AMN5:08 AME/NE
3/19very5:47 AMNW5:52 AME
3/20extremely6:30 AMW/NW6:36 AMSE
3/20moderately4:56 AMN/NE4:59 AME
3/21extremely5:39 AMNW5:43 AME/SE
3/22moderately6:21 AMW6:26 AMS
3/22moderately4:48 AME4:51 AME/SE
3/23extremely5:31 AMS/SW5:34 AMS/SE
3/26moderately9:05 PMS/SW9:07 PMS/SW
3/27very8:13 PMS8:17 PME
3/28extremely8:56 PMW/SW9:00 PMNE
3/29extremely8:03 PMSW8:09 PME/NE
3/29moderately9:40 PMW9:42 PMN/NW
3/30very8:46 PMW8:52 PMNE
3/31extremely7:53 PMW/SW8:00 PMNE
3/31somewhat9:31 PMW/NW9:34 PMN/NE

Predictions courtesy of Times later in the month are subject to change – for the most accurate weekly predictions, check

Meteor Showers: No Major Showers This Month

As has been discussed in previous articles, meteor showers are the result of the Earth passing through the debris field of a comet or asteroid. While the orbits of scores of these objects bring them close to Earth's orbit, a limited number produce enough debris to produce significant meteor shower activity. February and March mark yearly lulls in major meteor shower activity, with the next prominent shower being the Lryids that occur in April. The astronomy community recognizes many minor showers that are predictable in their timing and are predictably unimpressive. Those interested in seeing a full list should check out the American Meteor Society meteor shower calendar.

Learn A Constellation: Ursa Major

Ursa Major and the Big Dipper, including brightest star labels, the locations of Messier Objects, and an arrow to follow to the north star Polaris. Click for a larger view.

For the first time in this series, we turn our constellation attention to the north. Standing to the northeast and nearly upright on its handle in the late evenings in March is the Big Dipper. In what might be the original instance of "let's take this argument outside," the Big Dipper and Orion have vied for the title of "most famous group of stars" among the amateur astronomy community for as long as people have needed reason to argue. Once pointed out, the Big Dipper is unforgettable, making it an ideal anchor to begin one's hobby as a lifelong star-hopper. As a place to spend the evening observing, the Big Dipper and its surroundings offer a great location to discover a number of interesting astronomical objects.

The Big Dipper, bright and famous as it is, is NOT a constellation. It exists as the torso and tail of the constellation Ursa Major, "The Great Bear." The Big Dipper is one of a handful of widely recognized groups of stars called "asterisms," which one can loosely define as "any group of stars that aren't defined as a constellation." It would be a Herculean task to propose any changes to the 88 modern constellations, but you are welcome to define any group of stars that jump out at you as an asterism – and authors have done so in astronomy books as aids to learning the locations of stars and other objects in the nighttime sky.

The ties that bind Ursa Major to the history of civilizations in the Northern Hemisphere are as much a wonder to behold as the stars themselves. The Romans recognized Ursa Major as a bear, it is one of the few groups of stars with Biblical citation, and tribes and civilizations throughout central and northern Europe up through Scandinavia recognized this star grouping as a bear. Closer to our home, the Iroquois, Algonquian, and Lakota also recognized Ursa Major as a bear early in their star lore. There are compelling arguments that this continental meta-drift is *not* just coincidence, but might be part of a shared oral tradition of nomadic peoples that goes back some 13,000 years to the early population of North America through Beringia, the Bering Strait Land Bridge that existed between Russia and Alaska during the last Ice Age. If true, this would place Ursa Major up there with Orion and Taurus as a *very* old star group.

Like the belt, shoulder, and knee stars of Orion, one can't help but see the trees from the forest by spying the Big Dipper before the dimmer stars of Ursa Major. The three handle stars, Alkaid, Mizar, and Alioth, connect at the dimmer star Megrez to the remaining bowl stars Dubhe, Merak, and Phecda.

Turning our attention to the middle of the handle, a fun game to play at public observing sessions is to ask "How many stars do you see at Mizar?" Those with good vision will see two – Mizar and its dimmer companion Alcor. The history of what follows is not set in stone, but is not really in dispute either – the observation of Mizar and Alcor was used by the Roman Army as an eye test for soldiers. Those who could see both had excellent vision and were candidates for lookouts. Following that logic, those who could only see Mizar were assured never to see a big battle from a safe distance. I suspect that those who couldn't see Mizar either were assured never to see a battle from behind those who could. Alcor and Mizar turn out to be much more complicated than just a simple pair – Mizar is, in fact, a double-double! Magnification reveals Mizar to be a bright pair of stars, while professional equipment reveals each of these stars to themselves be a pair of closely-spaced stars, all bound gravitationally. The dimmer Alcor is itself a binary, making for a combined grouping of six stars.

The seven Messier Objects within Ursa Major, including M40 (from NOAO/AURA/NSF), M82 and M81 (ESA/Hubble), M97 (dam Block/NOAO/AURA/NSF), M101 (ESA/NASA), M108 (Hunter Wilson), and M109 (Hunter Wilson). Click for a larger view.

Within the borders of this massive constellation reside seven Messier Objects. M40 is a double star that very clearly doesn't seem to be a fuzzy object. Its identification as a Messier Object has been labeled by some as "Messier's greatest mistake." M81 and M82 are a pair of gravitationally-interacting galaxies beyond the bowl and above the front shoulder of Ursa Major. M97, the Owl Nebula, is well within the field of view of Merak in binoculars – but you will need very dark skies and excellent dark adaptation to ever see this object. The Pinwheel Galaxy, M101, is just at the edge of 10×50 binoculars with Mizar placed at one edge of your field of view, but is bright enough for binoculars. Galaxies M108 and M109 round out the Messier list along the bottom of the bowl. Far from street lights and the Moon, these seven are all possible to see with good dark adaption, but patience and a reduced expectation of their visual quality is key. In all seven cases, you may find that your hands are not steady enough to easily see these wispy objects under magnification. Even for binocular viewing, I recommend a decent tripod and binocular tripod mount to improve your views.

Dr. Damian Allis is the director of CNY Observers and a NASA Solar System Ambassador. If you know of any other NY astronomy events or clubs to promote, please contact the author.

Original Posts:


Some Light Science Reading. The Constellations: Orion

As first appeared in the April 2012 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Image generated with Starry Night Pro 6.

Much can be said about the old hunter Orion. To Central New York observers, it had (until very recently) been the case that Orion made his way across the Night Sky during the coldest and least hospitable (to most nighttime observers) months of the year. Conditions would keep observers in hiding from him (some of the best CNY observers I know would risk surgical strikes on the Orion Nebula with their fastest to set-up and tear-down equipment). The abbreviated winter of 2011/2012 and reasonably early start of the SAS observing season have provided us with excellent opportunities in the past few months to make Orion The Hunter now the hunted. The mid-April observing session will be the last "official" opportunity to observe Orion before he disappears behind the Western horizon until the most nocturnal of us can next see him in our Eastern sky before sunrise in late August. I then take this opportunity to discuss Orion, one many CNY/SAS members may know the best by sight but may know the least by observing attention.

One of the topics covered in the 2011 SAS lecturing series was how we observe. Not the discussion of optics or the physics of planetary motion along the ecliptic, but the visual and mental mechanisms we use to translate the photonic triggers in our retina into mental pictures of celestial objects. Orion was the astronomical example I used to describe Pareidolia, how we impose a kind of order on things we see despite that order not being present in the actual collection. When you look at a cloud, you may see a face, an animal, or something your mind triggers as being something it clearly is not. I often placed the infamous "Face On Mars" next to the Constellation Orion to show clearly how we see what we think we see despite all reasonable evidence to the contrary (or the two can be mangled together, as shown below). The clouds may look like an animal, the "Face On Mars" looks unmistakably like a shadowed face, and Orion, as it happens, has looked like a human figure to virtually all peoples for as long as we have record of Constellations, the same way Scorpius has appeared as a scorpion to every civilization for which this little monster was part of the local biosphere.

Pareidolia is not just for cognitive neuroscience! One of the keys to learning the sky I discussed last year was to let your mind wander while staring at the sky and see if certain things jump out at you. The constellations are, for the most part, made up of the most reasonably bright star groupings, but if you see any type of geometry that makes some part of the sky easy to identify, run with it. This same philosophy may be responsible for the rise of the asterism, or "non-Constellation star grouping," as the distillation of mythological complexity into more practical tools for everyday living. For instance, I suspect everyone reading this can find the asterism known as the Big Dipper, but how many know all of the stars of its proper Constellation Ursa Major? Our southern tree line and Cortland obscure some of the grandeur of Sagittarius, which means we at the hill identify the location of its core (and several galactic highlights) by the easy-to-see "teapot." The body of Orion is a similar case of reduction-to-apparent, as the four stars marking his corners (clockwise from upper left)…

Betelgeuse (pronounced "Betelgeuse Betelgeuse Betelgeuse!" – marking his right shoulder; a red supergiant of very orange-ish color even without binoculars)

Bellatrix – the left shoulder (so you now know the Constellation is facing us as originally defined) – a blue giant known also known as the "Amazon Star"

Rigel – the left foot; a blue supergiant and the star system within which the aliens that make the Rigel Quick Finder reside

Saiph – the right foot; a star dim in the visible but markedly brighter in the ultraviolet. Saiph and Rigel are about the same distance away (Saiph 50 light years closer at 724 light years, a point to consider as you observe them both)

… and the three stars marking his belt (from left)…

Alnitak – A triple-star system 800 light years away with a blue supergiant as its anchor star

Alnilam – the farthest star of the belt at 1359 light years, this young blue supergiant burns as brightly as the other two, making the belt appear equally bright "al across"

Mintaka – 900 light years away, this is an eclipsing binary star system, meaning one star passes between us and the main star in its orbit (about every 5.7 days)

… are obvious to all, while the head and club stars require a longer look to identify.

Sticking to Naked Eye observing for a moment, Orion is not only famous for its historical significance and apparent brightness. Orion is ideally oriented to serve as an order of alignment for several nearby Constellations and is surrounded by enough bright stars and significant Constellations that curiosity alone should have you familiar with this part of the sky in very short order. As an April focus, it is of benefit that all of the Constellations we'll focus on either hit the horizon at the same time as Orion or they rest above him.

I've color-coded the significant stars marking notable Constellations in the image below. If you're standing outside on any clear night, the marked stars should all be quite obvious (we're talking a hands' width or two at arm's length). From right and working our way counterclockwise…

(RED) Following the belt stars to the right will lead you to the orange-ish star Aldebaran, marking the eye of Taurus the Bull. This is a dense part of the sky, as Aldebaran marks both the head of the Bull and also marks the brightest star in the Hyades star cluster (a gravitationally-bound open cluster 150 light years away composed of over 100 stars). Just to the right of this cluster is the "Tiny Dipper" known as the Pleiades (Messier 45), another dense star cluster worth observing at all magnifications. Both of these clusters are simultaneously easier and harder to find at present, as Venus ("1") is resting just above them, providing an easy way to find both clusters but plenty of reflected light to dull the brilliance of the two open clusters.

(ORANGE) Auriga, featuring Capella (the third brightest star in the Night Sky), is an oddly-shaped hexagon featuring a small triangle at one corner. Auriga, like Ursa Minor in last month's discussion, is made easy to find by the fact that the five marked stars are in an otherwise nondescript part of the sky (relatively dim generally, but brighter than anything in the vicinity). Venus will dull Hassaleh (Auriga's closest star to Venus and the two open clusters below it) but Elnath and Capella will be easy finds.

(YELLOW) Castor and Pollux, the twins of Gemini, are literally standing on Orion's club. Making an arrow from Mintaka (the right-most star of the belt) and Betelgeuse will lead you to Alhena (Pollux's left foot), after which a slow curve in a horseshoe shape will give you the remaining stars.

(GREEN) Canis Minor is two stars (which is boring), but is significant for containing Procyon, the 7th brightest star in the Night Sky (which means it will be an EASY find). But don't confuse it with Sirius, which is the big shimmering star in…

(BLUE) Canis Major is the larger of Orion's two dogs and contains Sirius ("The Dog Star"), a star so bright (magnitude −1.46) and so close (8.6 light years) that it appears not as a star but as a shimmering light. Some would say an airplane, others would say a hovering UFO. Part of my duties as president involve intermittently explaining that it is not the latter.

And, with respect, Monoceros is an old Constellation but not a particularly brilliant one. Having Canis Minor and Canis Major identified will make your identification of Monoceros quite straightforward.

We now turn to the other "stellar" objects in Orion, composed of three Messiers and one famous IC. M78 is a diffuse nebula almost one belt width above and perpendicular to Alnitak. You will know it when you see it. M43 and M42 (marked as "4" in the image below), on the other hand, are so bright and close that you can see their nebulosity in dark skies without aid of any optics.

M42 – The Orion Nebula is, in the right dark conditions, a Naked Eye sight in itself. For those of us between cities, even low-power binoculars bring out the wispy edges and cloudy core of this nebula. For higher-power observers, the resolving of Trapezium at M42's core serves as one of your best tests of astronomy binoculars (I consider the identification of four stars as THE proper test of a pair of 25×100's. Ideal conditions and a larger aperture will get you six stars total). You could spend all night just exploring the edges and depths of this nebula. You can take a look back at the Astro Bob article in the April 2012 edition of the Astronomical Chronicle (From My Driveway To Orion, Nature Works Wonders) for a more detailed discussion of this part of Orion.

M43 – de Mairan's Nebula is, truth be told, a lucky designation. M43 is, in fact, part of the M42 nebula that is itself a small part of the Orion Molecular Cloud Complex (not THAT'S a label). M43 owes its differentiation to a dark lane of dust that breaks M43 and M42, just as the lane of dust in our own Milky Way we know as the "Great Rift" splits what would otherwise be one continuous band of distant stars the same way a large rock in a stream causes the water to split in two and recombine on the other side.

Finally (and the one you'll work for), IC 434, the Horsehead Nebula, lies just to the lower-left of Alnitak (1). The Horsehead is itself a dark nebula, a region absorbing light to make it pronounced by its difference from the lighter regions around it. To put the whole area into perspective, The Horsehead is itself STILL within the Orion Molecular Cloud Complex. The sheath of Orion's Sword and nearly the entire belt is contained in this Complex, like dust being rattled off with each blow from Orion's club.

I close by taking a look at the perilously ignored club attempting to tear into Taurus. At present, asteroids surround Orion's Club like pieces of debris flying off after a hard impact. All are in the vicinity of 12th magnitude (so require a decent-sized mirror), and all are also moving at a sufficiently fast clip that their paths can be seen to change over several observing sessions (if, by miracle, enough clear days in a row can be had to make these measurements). I have highlighted the five prominent ones in the image below.

Is it an oddity to have Orion so full of asteroids? Certainly not! Orion is placed near the ecliptic, the apparent path of the planets in their motion around the Sun. Orion's club just barely grazes the ecliptic at the Gemini/Taurus border, two of the 12 Constellations of the Zodiac, the collection of Constellations that themselves mark the ecliptic. As nearly all of the objects in the Solar System lie near or within the disc of the Solar System, you expect to find all manner of smaller objects in the vicinity of the Zodiacal Constellations. In effect, Orion's club is kicking up different dust all year long as the asteroids orbit the Sun. You only have a few more weeks to watch the action happen before Orion's return in the very early early morning of the very late summer.

– Happy Hunting, Damian