It’s February, the year’s shortest month - a necessary consequence of organising an odd number of days (measured more accurately as 365 1/4 days in a true tropical year) into even amount of months in that particular year. Before the Gregorian reform of the calendar year, which established the conventional pattern of months we use today, the Julian calendar was in effect, giving a much more complicated method of organisation of months. Every leap year, there was a 13th ‘Leap Month”, called as Mensis Intercalaris - more popularly known as Mercedinus or Mercedonius. This was normally around 23 days in length and was designed to synch the calendar up with the seasons. The reason for this is the relative shortness of most months in the Julian calendar, all of which were 29 days, bar March, May, July and October, which were 31 days in length. More confusingly, the regularity of the insertion of Mensis Interclaris into the calendar was decided by one man - the Pontiflex Maximums, who was responsible for many other decisions, both practical and religious. The insertion or deferment of a leap month - whether it was needed or not - was often used politically to extend or cut off periods of public office and was thus potentially subject to abuse. We must be thankful that the order given to our calendar by the Gregorian reform, though a political act in itself, was put forth as the result of careful scientific observation and the application of reason to the results of these observations. When political expedience trumps scientific rationalism, the historical record rarely shows that this benefits the greater long term good.
But however short the month, keep looking up - as ever, there’s plenty to see in the skies above, wherever you find yourself.
The Moon begins the shortest month of the year in the non-Zodiacal constellation of Cetus. A 4-day old Crescent, it is strung out in a line in the early evening sky, alongside the brilliant Venus and the fainter Mars. This is the beginning of the "High Spring Crescent" phase of the year, where the Moon's Waxing Crescent phase occurs in a reasonably steep part of the ecliptic - from a northern hemisphere perspective at least. This leads to a larger than average separation from the horizon and also some spectacular lighting conditions for evening observations. As the Moon climbs higher in the ecliptic over the next few days, those in the northern parts of the planet are encouraged to make the most of this opportunity.
The Moon reaches First Quarter on the evening news of the 4th February, while in Taurus. The following evening, the Moon makes one of its regular jaunts through the Hyades star cluster, which forms the V-shaped head of Taurus, occulting many members as it does so.
The Moon becomes Full on the night of the 10th/11th. This coincides with a Penumbral Lunar Eclipse in Leo, which is visible in its entirety from Europe and Africa and will be partially observable from much of Western Asia and Northern and Southern America. A Penumbral Eclipse is not as spectacular as a Total Lunar Eclipse, as Penumbral Eclipses occur when the Moon enters the weaker, more diffuse shadow caused by the Earth's atmosphere, rather than the full shadow of the Earth itself. Nonetheless, a Penumbral Eclipse can be a very interesting and potentially beautiful event to observe and photograph. Much information can be gleaned about the condition of the Earth's atmosphere from the depth of the Penumbral shadow. After volcanic eruptions, the shadow of the Penumbra has been observed to be almost as dark as the Umbra itself. The lack of major volcanic activity worldwide points to a lighter eclipse this time, but man-made pollution also has a part to play in the equation too.
The Moon, First Phase of Penumbral Eclipse, February 10th. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
The Moon reaches Last Quarter on the night of the 18th, while in the extreme western reaches of Scorpius. Two days later, it rises close to Saturn on the Sagittarius/Ophiuchus borders, the two separated by about 4 degrees. By the time the Moon Becomes New on the 26th February, it will have climbed from the extreme south of the ecliptic up to join the Sun in Aquarius.
We leave the Moon on the last day of the calendar month - the 28th - on the Pisces/Cetus borders. It is just two days old so will be extremely difficult to find in the evening sky. However, the brilliant Venus, just over 12 degrees to the north, can act as a useful guide to its whereabouts.
The Two Day Old Crescent Moon and Venus, 28th February. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Mercury begins the month of February as a morning target in Sagittarius, shining at a steady -0.2 mag, at a phase of just over 81% and an angular diameter of 5.6 arc seconds. It will be a difficult target to spot for those in the northern hemisphere, as it will skirt the horizon at daybreak, sitting at just under 5 1/2 degrees altitude (from 51 degrees N) as the Sun comes up.
By mid-month, Mercury will have decreased its separation from the Sun to 15 degrees and will be largely unobservable from the temperate northern hemisphere - though will be reasonably well-placed for those in the equatorial and southern parts of the planet.
By the time February reaches its conclusion, Mercury will be barely a week from Superior Conjunction (the opposite side of the Sun from Earth) and will be unobservable throughout the world.
The Inner Solar System, 1st February 2017. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Venus starts February in spectacular fashion as an evening target in Pisces. Blazing away at near-maximum brightness, the planet presents a -4.6 mag, 39% crescent phase, just under 40 arc seconds in diameter on the 1st. Venus is well-placed for observation all over the world and will stand 34 degrees high in altitude as the Sun sets (from 51 degrees N). On this particular evening, Venus will form a loose conjunction with both Mars and the Moon, from which it will be separated (in a westerly direction) by just under 5 1/2 degrees and just over 13 degrees respectively.
Venus, Moon and Mars, 1st February. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
By mid-month, Venus will have retained its dazzling brightness, still sitting at -4.6 mag, though will have decreased phase to 28.7%, while increasing angular size to 38.2 arc seconds. The reason for Venus retaining magnitude, while it decreases in phase, is simply due to the planet catching the Earth up on a faster interior orbit - which naturally increases the planet's angular size. Thus, while the illuminated phase of the planet decreases, the expansion of illuminated surface area keeps pace and compensates, subsequently retaining brightness as we see Venus from Earth.
By the end of February, Venus still sits at -4.6 mag, though is now a very thin crescent - just 17.1% illuminated - but a proportionally large 46.7 arc seconds angular size. By this point Venus will have surpassed Jupiter in angular diameter, being the largest member of the solar system from our perspective on Earth, apart from the Moon and Sun. The planet will continue to expand yet further as March progresses. Venus now stands just under 30 degrees high (from 51 degrees N) at Sunset - a magnificent target for visual and photographic astronomers alike.
Mars begins February as an evening object in Pisces, setting a little under 4 1/2 hours after the Sun. At +1.1 and 5.1 arc seconds diameter, it's hardly prominent, but worth a look if you have access to a reasonably powerful telescope.
The trend, as reported in previous Sky Guides, is definitely downwards as far as Mars is concerned. By mid month, the planet will have shrunk to 4.8 arc seconds diameter and +1.2 mag.
On the 26th February, Mars comes into reasonably close conjunction with Uranus, providing a useful signpost for the fainter outer gas giant. Sitting just over half a degree to the SE from Mars, as the Sun goes down, Uranus will present a +5.7 mag, 3.4 arc second disk.
Mars and Uranus, Sunset, 26th February (blue circle represents a two degree wide field of view). Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
By the month's end Mars, still a resident of Pisces, will present a +1.3 mag, 3.6 arc second angular size disc.
The solar system's largest planetary member begins February as a mag -2.2 target in Virgo. Rising at 11.13pm (GMT/UT, from 51 degrees N), Jupiter is still essentially the preserve if the morning observer, transiting as it does at 4.41am on the 1st. At 39.1 arc seconds diameter, it should be an impressive sight in telescopes of all sizes
Jupiter Great Red Spot and Io Transit, 2.35am GMT, February 9th. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
By mid-month, Jupiter has increased in angular size to over 40 arc seconds, but isn't noticeably brighter. By the 15th, the planet will rise at 10.17pm (GMT/UT, from 51 degrees N) and will transit at the earlier time of 3.46am.
This trend continues, and by the end of February, Jupiter will have increased in brightness to -2.3 and will now be 42.1 arc seconds in diameter. The king of the planets now rises at 9.22pm (GMT/UT, from 51 degrees N) and transits at 2.52am. We are steadily catching Jupiter up on our faster interior orbit and will be around 5 weeks from the Jovian opposition of Earth at the end of February.
The Ringed Planet begins the shortest month as a +0.5 mag target in Ophiuchus. At 15.6 arc seconds across, it is neither largest not the the brightest of planetary targets, but well worth seeking out in the morning sky. Rising at just under three hours before the Sun, Saturn stands a little under 14 3/4 degrees high at Sunrise.
By mid month, little has changed, Saturn is fractionally larger at 15.8 arc seconds, but in not discernibly brighter. It is still rising a little under three hours before the Sun.
Saturn and Moons, Sunrise, 15th February. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Saturn is joined in loose conjunction on the morning of the 21st by a Waning Crescent Moon in neighbouring Sagittarius.
By the end of February, Saturn will have made the transition into Sagittarius and will have increased angular size fractionally to 16.1 arc seconds, but won't appear to be any brighter. Saturn now rises a little after 3am (GMT/UT, from 51 degrees N), a little under 3 1/2 hours before dawn.
Uranus begins February as a +5.9 mag, 3.5 arc second diameter target on Pisces. It's an easy target for those with binoculars and reasonably dark skies and can even be glimpsed with the naked eye, if your eyesight and sky conditions are good enough.
The crescent moon will join Uranus in Pisces on the evening of the 2nd February and although it is jus under 5 1/2 degrees to the SE at Sunset, will still provide a handy reference point for locating Uranus.
As previously discussed above, on the evening of the 26th, the brighter Mars passes just over half a degree from Uranus - providing the opportunity to observe both planets in a low power telescopic field of view.
Neptune, being further west in the ecliptic, has a much more limited window for observation. The +8.0 mag, 2.2 arc second diameter disk is separated from the Sun by 22 1/3 degrees, setting around 2 1/2 hours after dusk on the 1st. However, as Neptune reaches Superior Conjunction in early March, we cannot expect to meaningfully observe the planet during the month.
After a relatively quiet period for cometary news, there are quite a few comets - some old periodic favourites, some new - worth mentioning and keeping one’s eye on for the next few months.
Firstly, Comet 2015 ER61 (PanSTARRS) is potentially the most exciting as it could reach brighter than faint naked eye magnitude in May 2017. As ever, caution is urged as far as any predictions go, but it will be interesting to see how this object develops. 2015 ER61 will be moving from the Scorpius-Ophiuchus borders, across Ophiuchus and into Sagittarius during February. It will be a morning object, visible in the predawn sky, at relatively low altitude from temperate northern climes. Mean magnitude predictions put this comet at around low naked eye visibility during the month, starting off at +6.5 mag and potentially brightening to around +5 mag as the month ends. The comet could well get even brighter towards its perihelion in May. It all depends if this is one of the comet’s first visits to the Inner Solar System - if it is, it is likely to be deeply frozen and may well be rather inactive, in comparison to if this were one of its later visits. The fact that the PanSTARRS survey initially classified ER61 as am asteroid, rather than a comet, due to distinct lack of cometary activity, may well suggest the former to be the case - we’ll just have to wait and see.
Comet C/2015 ER61 (PanSTARRS) during February. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Comet 2015 V2 (Johnson) will be lurking at around +9.0 mag as February begins, though will brighten - probably by about half a magnitude - as the the month comes to an end. Shuffling its way through Bootes and Hercules during February, Comet Johnson is brightening towards perihelion in June, where it may get to between +4 and +7.5 - a big margin of error, but the mean prediction puts it at around +6 mag, so it will hopefully be a good binocular comet, if not a spectacular naked eye object. Technically, Comet Johnson is circumpolar for much of the northern hemisphere, so should be visible all night. It will remain so until its drastic dive towards the Sun that pre-empts perihelion.
Comet C/2015 V2 Johnson movements through February and beyond (comet position 1st Feb). Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Comet 45/P Honda-Mrkos-Pajdusakova is a short period comet that will make a close approach of Earth this year - getting to its closest point of 12.6 million km (around 7.8 million miles) on 11th February.
Comet 45P/ Honda-Mrkos-Pajdusakova closest approach to Earth, 11th February. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
As the comet crosses Earth’s orbit a few days later on 14th February, it will appear to rocket across the sky during the course of the month, as demonstrated below. Predicted to be around 7th magnitude, Honda-Mrkos-Pajdusakova won’t be especially bright, but will be visible in binoculars throughout the month.
Comet 45P/ Honda-Mrkos-Pajdusakova path during February 2017. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Comet 2P/Encke returns for a record 63rd observed apparition in early 2017. First officially observed by Pierre Mechain, Charles Messier’s correspondent and discoverer of many of the Messier list of objects, in 1786, Comet Encke was not recognised as such by Mechain at the time (despite the Messier list being drawn up precisely to help differentiate between potential comets and deep sky objects). The comet was later reacquired by Caroline Herschel on its 1795 appearance and the legendary French comet hunter Jean-Louis Pons in 1818. Pons still holds the record for the number of comets discovered by one individual and it is testament to his skill as an observer that even after the German Astronomer and mathematician Johann France Encke received the honour of having the comet named after him, having completed calculations that tied previous appearances together, Encke still referred to this particular comet as “Pons’ Comet”. Still, like Halley’s Comet, Encke’s Comet refers not to its discoverer, but the man who calculated its orbit and did the mathematical detective work, which proved that previous observations were indeed the same object.
This time around, Comet 2P/Encke will be visible in the west after Sunset, a faint object, found just a little to the NW of Venus of 1st February. As the month progresses, it dips towards the Sun, brightening as it approaches Perihelion in early March. By the latter part of February, Comet Encke should be bright enough to find in binoculars, but really starts delivering in the last week of the month, hitting around naked eye brightness - though this will be tempered by having to wait for the Sun to have set far enough below the horizon to observe it. Once Astronomical Twilight ends, Comet Encke will be a little over 10 degrees above the horizon (as seen from 51 degrees N) on the evening of 24th February - though handily, Venus will still be around to point the way, being almost exactly 7 degrees higher in the same area of sky (when seen from the northern hemisphere).
Comet 2P/Encke during February and beyond (comet position shown 1st February). Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Last but not least is periodic comet 41/P Tuttle-Giacobini-Kresak, which is to be found moving northward from the feet, through the head of Leo during February. Although not bright at the moment - registering between 9th and 10th magnitude during the month, Tuttle-Giacobini-Kresak will increase in brightness as it passes less than 0.14 AU (22 million KM, 13.78 million miles) over the North Pole of the Earth, during March and early April, when it may well make low naked eye brightness.
The Planetary Science Institute is asking volunteers from all over the world to send them images of comets 41P/Tuttle-Giacobini-Kresak, and 45P/Honda-Mrkos-Pajdusakova in 2017 and comet 46P/Wirtanen in 2018 for their 4*P Cometary Morphology Campaign, which aims to monitor and map in close to real time the development of Coma features in these three comets. The kind of images they require are not beyond the reach of amateur instruments or equipment, so why not try to contribute? Details of the 4*P Cometary Morphology Campaign and further requirements can be found here:
Last month's Deep Sky Guide covered the great swathe of sky taken up by the constellations of Monoceros, Canis Major and Minor and Puppis. This month we turn our attention to the two neighbouring Zodiacal constellations of Gemini and Cancer and their more northerly neighbour, the large, yet sparse Lynx.
Gemini, Cancer and Lynx. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars, www.southernstars.com.
Of the three constellations, Gemini, the twins, is by far the most prominent to the naked eye, containing a good deal more in the way of bright stars. Castor, (Alpha Geminorum), is a fine double star and an easy target in small instruments. Consisting of two stars, A and B, of +2 and +2.9 mag respectively, Castor's elements are currently widening and are separated by 4.5-5 seconds of arc. Castor's double nature was discovered in 1678 by Cassini (he of Saturn's ring division fame, amongst many other discoveries) and bears the distinction of being the first gravitationally bound object to be identified beyond the reaches of the Solar System. Castor A and B's orbit about a mutual gravitational point takes around 467 years to complete, but both stars are also in turn doubles, with much fainter M-class dwarf companions. In addition to these companions there is also present in the system a further pair of gravitationally bound M-class stars. This makes Castor not just a double star, but a sextuple - quite a collection! Sadly, only the primary elements are observable in amateur instruments.
To the Westerly reaches of Gemini, is to be found M35. M35 is a very prominent star cluster, at +5 mag, easily picked in small telescopes and binoculars and can also be seen with the naked eye from a reasonable site. Consisting of well in excess of 100 observable stars (mags 6-13th), M35 was first noted by Astronomer Philippe Loys de Cheseaux in 1745. Also included in the Uranographica Britannica by John Bevis in 1750, M35 was catalogued by Messier in 1764, who credited Bevis with its discovery.
M35 Cluster. Image Credit: Atlas Image [or Atlas Image mosaic] obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Public Domain.
Many of the 100+ observable stars are types G and K stars - similar in class to our Sun- though these seem to be of a considerably larger mean size than main sequence. M35 is tentatively aged at about 100 million years - about the age of the nearby M45, (the Pleiades) though problematically, stellar evolution is thought to be considerably more advanced in the case of M35. Does this mean that M35 is in fact older, or are the Pleiades actually younger? Further observation and theories will be needed to explain this anomaly.
In the background sky to M35 lies the fainter (+8 mag) open cluster NGC2158, though this is nearly six times further away than M35's 2800 light years. In addition to this, there is also the yet fainter and more compact IC2157 cluster (+8.4 mag) - making this an extremely rich area for sweeping with virtually any type of optical aid.
Drifting Eastward, 2 1/3 degrees East of the star Wasat (Delta Geminorum) is the fabulous Eskimo Nebula, NGC2392. This Planetary Nebula supposedly resembles an Eskimo's head, surrounded by the fur of an Arctic Parka hood. A reasonably compact 0.8 arc minute across (about 2/3rds the size of the Ring Nebula, M57), the Eskimo is only +9.19 mag, though its compact size makes its surface brightness quite high and it takes magnification well. Discovered by William Herschel in 1787, it is perhaps surprising that it wasn't noticed by earlier observers - though this is most likely down to its small size. OIII filters reveal more of the two stages of the object: it's tenuous outer shell and the gleaming, brighter interior. Larger instruments reveal more of the complex structure of the internal part of the Eskimo - its radial double shell of expanding gasses and fine filaments blown by cosmic winds form its central star. This central star shines at +10.5 mag and is relatively easy to spot in most instruments. The nebula is thought to lie at 2800-3000 light years distance.
Eskimo Nebula, Hubble Space Telescope Image. Image Credit: NASA/ESA. Public Domain.
Further South from the Eskimo is another older, larger and fainter object - The Medusa Nebula (Abel 21). Whereas the Eskimo is small and comparatively bright, the Medusa is large - at 10 arc minutes across it is a third the diameter of the Full Moon. Telescopes of 8-inches + aperture, coupled with a good OIII filter and a dark site will be needed to seen the Medusa. Although listed as being +10.19 mag, this is spread out over a significant area of sky, so it is in long duration astrophotography that the wonders of the Medusa really start to reveal themselves. A modest aperture telescope will be needed and a sturdy equatorial mount, capable of being autoguided , will be needed to attempt to image this object. Images reveal the serpent-like tendrils of nebulosity that give this mysterious object its name - its namesake Medusa being the Gorgon who had snakes for hair in classical Greek mythology. The stare of Medusa was reputed to turn people to stone, though staring at this nebula through a large telescope will be a much more pleasant experience… The Medusa lies about half the distance from us as the Eskimo Nebula - 1500 light years and is around 4 light years in diameter. Opinions were divided on the true nature of the Medusa: George Abel, its discoverer thought it to be an old planetary nebula, whereas many considered its irregular nature to indicate it was a supernova remnant. Narrowband imaging has revealed the true extent of the Medusa's helical hourglass figure - making it much more likely to be, as Abel initially suggested, a planetary nebula.
The Medusa Nebula. Image Credit: Joel Schulman. Creative Commons.
The Zodiacal constellation of Cancer is not a particularly prominent constellation, comprising as it does of stars no brighter than the 3rd magnitude. Of its principle stars, Iota Cancri is probably the most interesting for amateur observers. This star marks the most Northerly point of the main constellation and is a double star of +4.01 and +6.57 mags. The primary star is a yellow G-type star, the secondary a white A-type main sequence star. Separated by 30 seconds of arc, these are an easy and attractive pair for small telescopes. The angular separation of the two has not changed radically for over a century, but it has been established the two are related. It is estimated their orbital period is over 65,000 years.
Nine degrees to the South of Iota Cancri lies one of the jewels of the night sky, the bright, expansive open cluster of M44, The Beehive or Praesepe. At +3.09 mag this cluster is an easy naked eye object from a reasonable observing site and at over a degree in size, is pretty unmissable! Recognised since antiquity, M44 was known as Phatne - "The Manger" to the ancient Greeks (Praesepe being the Latinised translation of this title), though its first datable mention in literature came in 260 BC, when the Greek poet Aratos called it the "Little Mist". M44 was also contained in Hipparchus' star catalogue of 130 BC. The Beehive as a name seems apt, as the core of M44 could be argued to resemble a natural hive, with outlying stars being "the Bees" hovering around it.
M44, The Beehive. Image Credit: Miguel Garcia. Creative Commons.
Containing over 1000 individual stars (over 75 of which are observable to the smallest amateur telescopes), M44 appears to share a proper motion with the Hyades in neighbouring Taurus, which seems to suggest a common point of origin.- both clusters seem to be of a similar age too (around 600-730 million years). The Beehive lies 570-610 light years away from us and is estimated to be about 12 light years in diameter (though its tidal influence reaches much further). This cluster should be seen by everyone - just grab a pair of binoculars. Its mix of stellar components make for a lovely imaging opportunity too.
Eight degrees to the South East of the Beehive, another open cluster, M67, is to be found. Although fainter and more compact that M44 at +6.90 mag and 25 arc minutes, it is in its way as attractive a target as its neighbour. Discovered by Johann Koelner in the late 1770s, M67 was catalogued by Messier in 1780.
Comprising of about 100-or-so observable members (out of a total of over 500 stars), many of which are similar it class to the Sun, M67 is one of the oldest clusters in our galaxy. It is thought to be around 4 billion years old - nearly as old as our own Sun and lies 3000 light years away. M67 does also contain some "blue stragglers" - stars that technically speaking it should not contain. Whether these have been swept up by M67 during its journey around our galaxy or not is a question that, to date, remains unanswered. Observers using higher power magnifications will resolve some spectacular chains of stars in M67. It truly is a lovely object.
Further Southeast (by just under 7 degrees) from the delights of M67 is a much more challenging target, the beautiful spiral galaxy NGC2775. Though not intrinsically conspicuous at +10.10 mag, it is a compact target at 4.3 x 3.3 minutes of arc and has a comparatively bright core. Lying some 60 million light years away, NGC2775 is an exotic blend of a spiral structure and large elliptical core, which itself is ringed by pronounced hydrogen regions. The arms of the outlying spiral sections are very finely structured, though this is only really visible in long duration images. Visually, NGC2775 is visible with a reasonable-sized instrument, though a larger scope may on occasion show interactive stream of material from NGC2777, which is tidally interacting with its larger neighbour. Whilst a challenge, NGC2775 has been the site of some 5 Supernovae since the mid-1980s, so who knows what you may find there?
NGC2775, Hubble Space Telescope Composite Image. Image Credit, Nasa/ESA. Public Domain.
Cancer contains many galaxies between the +12-14 mag range. Being located so close to the Leo, Leo Minor and Hydra galaxy clusters, it would seem a fairly safe assumption that Cancer's galaxies are gravitationally clustered. Studies of proper motion based on spectral shift have confirmed, however, that these galaxies are not related. Still, there is much for owners of large telescopes and astrophotographers to enjoy galaxy-wise in Cancer. Although many of these objects are challenging and are not as easily-observed as those in the adjacent constellation of Leo, there is another reasonably well-seen galaxy in this area of sky, just a short hop over the Northern border of Cancer into the constellation of Lynx - NGC2683, otherwise known as the "UFO Galaxy".
Discovered in 1788 by William Herschel, this spectacular object lies almost edge on to our line of sight on Earth and subsequently has a very reasonable surface brightness. Covering an area of sky 9.3 x 2.1 arc minutes, NGC2683 is easily seen in large telescopes, whereas smaller scopes will just resolve its bright elongated core. The foreshortened spiral arms of the UFO galaxy are laced with dust lanes, one of the major examples of this practically bisects the core from our perspective.
NGC2683, Hubble Space Telescope Image. Image Credit: NASA/ESA. Public Domain.
It is thought that NGC2683 is reasonably close to the Milky Way group, from a cosmic perspective, though different sources list its distance as a widely variable 16-33 million light years away. The UFO Galaxy's core is often remarked upon as appearing yellow - indeed, it seems that there are a larger population of older yellow and red stars stars in this galaxy than average and that there is little star-forming activity taking place within the system. Compared to our galaxy, though less massive and luminous, NGC2683 boasts twice the number of globular clusters.
Lynx, whilst obscure to the naked eye observer, also contains another galaxy of note, NGC2537, otherwise know as the Bear Paw Galaxy. This barred spiral is located some 14 3/4 degrees to the North of NGC2683 - giving a good idea how large Lynx is as a constellation! The Bear Paw is a very compact object, being some 1.7 x1.5 minutes of arc across - and although officially classed as a +11.69 mag object has a high surface brightness because of its diminutive area and is rather more visible than many objects of similar listed magnitude. The Bear Paw is so-called due to the areas of brightness which form a patchy pattern, which somewhat resemble the paw print of an animal. Whether it is that of a Bear or not, we leave you to draw your own conclusions! NGC2537 is thought to lie some 22 million light years away from our own Milky Way Galaxy.
Text: Kerin Smith