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Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

For those in northern latitudes similar to the southern part of the UK, and northern mainland Europe, August brings a welcome return of darkness - though those further north in latitudes similar to Scotland and Scandinavia will have to wait until the mid part of August to enjoy it.  Permanent Astronomical Twilight will continue for those in latitudes around the Shetland Isles and further north until the tail end of August, but for the rest of us, true darkness can be enjoyed throughout the month.  For those readers in the southern hemisphere, Midwinter is now past and the nights are beginning to get shorter.  But wherever you find yourself in the world, as ever, there's plenty to see.


The Solar System

The Sun

It's rare that we cover the Sun in the monthly sky guide, which doesn't mean that it is without interest - far from it.  However, this month brings a significant event that is well worth commenting on.  On 21st August the track of a total solar eclipse will cut a swathe through the USA: from landfall on the Pacific West coast in Oregon, through the states of Idaho, Wyoming, Nebraska, Kansas, Missouri, Kentucky, Tennessee, Georgia and exits into the Atlantic Ocean, through South Carolina.  Although only those on the central track, a few miles wide will witness the eclipse's totality, it will be visible as a partial eclipse over a huge area, which will take in the large parts of the Pacific, including Hawaii and the eastern extremes of the Russian Federation, the entirety of Central America and the Caribbean, plus much of the northern half of South America, most of the Atlantic Ocean and large parts of West Africa and Western Europe.  As such, assuming reasonable weather, this eclipse stands a good chance of being the most widely-observed astronomical event of all time.  Around a billion people sit underneath the eclipse's sphere of influence and although not everyone will see it, public awareness of the event - particularly in the USA - is high.  


NASA Guide to the extent of visibilty of the solar eclipse of 21st August 2017, calculation and projection by Fred Espinak.  Image credit: Public Domain

For those in Western Europe, including Iceland, most of Spain, Portugal, Ireland, Scotland, Wales, England, Belgium, the Netherlands, some of Norway, Sweden, Denmark and the western extremes of Germany and around half of France, the August 21st eclipse will be very partial and will occur around Sunset.  The more westerly you find yourself, the better the chance you'll have of observing it.  A clear westerly horizon will be an absolute necessity - so if you have a western horizon over the sea, this will give you the best chance of seeing what's visible.  It is always worth re-emphasising the old adage: do not attempt to observe the Sun without proper filtration.  Sunglasses, smoked glass, welders glasses are not enough - you will need to use properly certified solar film, solar polymer filers or glass solar filters.  Of course, H-Alpha and Calcium-K or Herschel Wedge equipped telescopes are perfectly safe to use, though do check the internal makeup particular instrument you're using before installing a Calcium-K or Herschel Wedge - these two should only really be installed in refracting telescopes of under 6-or-so inches of aperture.  If you've got a reflector, then a full aperture white light filter or film is recommended. A dedicated solar scope such as those available from Lunt Solar Systems or Coronado Solar are the safest bet for long term solar observations - as these will also show spectacular solar prominences and other atmospherics. Solar Eclipse glasses are also available, though if you're trying to observe the extreme partial eclipse from Europe, white light solar binoculars will be needed at the very least to provide the magnification required to observe the event. 


For those in the U.K., the eclipse will begin at around 7.40pm in the evening, with both Sun and Moon under 3 degrees from the horizon. At this altitude, atmospheric refraction will cause some distortion to the Sun's regular round outline, so it will be interesting to see how much of the ingress of the Moon can be observed. Maximum eclipse occurs at around 7.56pm, with the Sun barely 1 1/2 degrees above the horizon. Though as the Sun is currently a resident in Leo it and the Moon set at quite a shallow angle from temperate northern latitudes, which leads to a longer potential window of observation for those of us in these locations, than had the eclipse occurred at another time in the year. 


Solar Partial Eclipse from 51N/0W, 7.45pm (BST), 21st August. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

It's worth restating: this is going to be a challenging event to witness from European locations. Decent observing elevation, a flat horizon and luck with the weather and atmospheric conditions will all be needed. But there's nothing that we Astronomers enjoy like a challenge - we at Telescope House will be on the lookout. If you decide to as well, we wish you good fortune in the attempt, but urge you to remember our solar safety warnings. If you're in the USA or traveling these to see the eclipse in full - it should be an event that lingers long in the memory. Not matter where you find yourself, if you have any pictures you'd like to share, please send them to us, we'd love to feature them in next month's Sky Guide.


The Moon


 The Moon plays an obvious part in the solar eclipse of 21st August, but it is not the only eclipse it is involved in this month, as there is a Partial/Penumbral lunar eclipse on the evening of 7th August - depending on where on Earth you witness it. 

 The Moon begins August at a 9 day old Waxing Gibbous phase in Scorpius, low on the horizon for those in the temperate northern hemisphere. 

 Full Moon occurs on the night of the 7th, when our natural satellite rises in Capricornus over Europe, already well into the eclipse. The Penumbral phase of a Lunar Eclipse is never as spectacular as the Umbral phase, as the Moon only enters the shadow cast by the atmosphere of the Earth, rather than the deep shadow of our planet. Nevertheless, a Penumbral Eclipse can throw up some interesting colouration - particularly when major volcanic eruptions have occurred in the recent past. Some Penumbral Eclipses have been nearly as dark as the Umbral phase of a Total Lunar Eclipse - though this is not necessarily expected to be the case with August's. 

 Most of the Eastern Hemisphere of the planet will be able to see the partial Umbral phase of this eclipse - though for residents of the UK and those further west, we will only be able to see this eclipse as Penumbral. The Moon rises at just before 8.30pm (BST) and the eclipse's phase will diminish the higher the Moon rises in the sky.  By around 9.50pm (BST), the event will be over, so be sure to remember to catch it early in the evening. 

Moonrise, mid-penumbral eclipse, 7th August. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

 Lunar Eclipses are simple enough to photograph and you can easily set up multiple wide field exposures to capture the Moon sliding out of the Earth's shadow. The focal length of your camera's lens doesn't have to be dramatically long in order to record a real tonal difference in the Moon's shade inside and outside of the event. If you do record the Eclipse photographically, again, we'd love to share the results. 

 Beyond Full, the Moon reaches Last Quarter on the 15th when in Taurus. After which it reaches New in Leo on 21st, as previously covered in the report on the forthcoming Total Solar Eclipse above. 

 The Moon then becomes an evening object and reaches First Quarter on 29th August while in the non-Zodiacal constellation of Ophiuchus. 

 The end of August finds the Moon as a Waxing Crescent in Sagittarius, at about 73% illumination.



The beginning of August finds Mercury as an evening target, some 27 degrees east of the Sun and sitting around 5 1/2 degrees high in the west at sunset (from 51 degrees N).  At +0.5 mag, and 8 arc seconds in angular diameter, it isn't especially prominent. 

 By mid-month, Mercury has decreased its separation from the Sun to just over 18 1/2 degrees, but crucially for those in mid-northern latitudes, now sets practically in line with the Sun, making observations challenging to say the least. A lower magnitude of +1.8 compounds this difficulty. 

 Mercury continues its dip towards the Sun through the next 12 days, until it reaches Superior Conjunction with the Sun on the 27th August. After this point, the innermost planet becomes a morning object, though will still be too close to the Sun for meaningful observations until early September.


Mercury, Sunrise 31st August. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,



Our nearest planetary neighbour puts on a stunning show in the morning sky during August. Shining at -4.0 magnitude and presenting a 14.5 arc second diameter disk, illuminated by 74% on the morning of the 1st, Venus stands just under 25 degrees high at sunrise (from 51 degrees N).

 As the month progresses, Venus dips a little towards the Sun, but counter-intuitively, increases its height at sunrise somewhat to just under 26 degrees (again, from 51 degrees N). This is simply down to planetary geometry: Venus at this point is located at around the highest northerly point in the ecliptic (the path that the major planets follow around the sky) in Gemini. For observers in the northern hemisphere, this causes the most extreme angle of setting of a given object. However, the opposite is true for those attempting to view Venus in the southern reaches of our planet at this point in time. 

 The end of August finds Venus having moved from Gemini into neighbouring Cancer. The planet is still at -4.0 mag, though has decreased in angular size to 12.5 arc seconds across, but increased its phase to 83.5 %. It stands just a shade under 25 1/3 degrees high, practically due east at sunrise on the morning of the 31st (from 51 degrees N).

Venus, Sunrise 15th August 2017 - Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,



Mars has just emerged from Superior Conjunction with the Sun and - although technically a morning object - is unobservable in the morning glare for much of August.  By the month’s end, Mars will sit around 8 1/3 degrees high at sunrise, though at +1.8 mag and just 3.6 arc seconds across will be neither easy nor particualrly interesting to observe.  However, we are now on the downwards slope to next year’s Martian Opposition, so Mars will continue to get better and better from now on, though it will be the best part of a year until it is at its brightest again.



At -1.9 mag and 34.2 arc seconds across on the 1st of the month, Jupiter is extremely easy to spot in the SW at sunset.  However, the window for Jovian observation continues to narrow, so make the most of the planet while it is still visible.  Setting around 2 hours after the Sun, and reasonably low in the sky in Virgo, Jupiter will reman a vibrant sight in binoculars. And telescopes of all sizes, though its elevation - 17 degrees above the horizon at sunset from 51 degrees N - means for those of us in the northern hemisphere, atmospherics conditions will play a massive part in what we can or cannot see of Jupiter and its coterie of satellites.  

 By mid-August, Jupiter has decreased a little in brightness to -1.8 mag and shrunk a margin to 33.1 arc seconds diameter.  The King of the planets now sets around an hour and a half after the Sun.

 By the month’s close the observational window has tightened to just over an hour between the setting of the Sun and Jupiter.  Now just 10 degrees in elevation (from 51 degrees N), Jupiter has dimmed a little further to -1.7 mag.  It is still brighter than anything else in the sky, bar the Sun and Venus, but will not be at its best for northern temperate observations, though those in the equatorial regions of the Earth will still see it standing a much healthier elevation of over 43 degrees high at sunset.

 To extend your potential window for Jovian observation, you can always try to find an view the planet during the daytime.  Daylight observations of Jupiter are perfectly possible, though solar safety is obviously advisable to consider when attempting to pick the planet out during daylight hours.  If possible, pick a location where the Sun is shielded from view to be on the safe side.

Jupiter at Sunset, August 15th 2017 - Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,



Saturn is still well-placed for evening observations during August, though as a resident of Ophiuchus is rather low for those of us in the northern hemisphere. Given the planet’s brightness - +0.3 mag at beginning of the moth, it will be nowhere near as prominent than its neighbour Jupiter, though being much further east in the ecliptic, is around for much longer during true hours of darkness. 

 Saturn stands some 16 degrees high in the sky at sunset (from 51 degrees N) on the evening of the 1st - and will be a glorious sight in telescopes of any size - though you will need to use magnifications of around 30-40x in order to truly pick it up as a rigged object.  Saturn’s rings are practically wide open at the present time and it will be relatively straightforward to pick out the major gap  - the Cassini Division - in their structure with small telescopes, if the atmosphere is playing ball, of course.  The Cassini division is often a good test of a telescope and should be resolved in instruments of around the 80-90mm aperture range at magnifications of around 100x - though atmospheric scatter when the planet is low in the sky is often the deciding factor, rather than the telescope or eyepiece combination itself.  Why not dig out the eyepiece that gives around 100x magnification and try the test out on your own telescope?  It is, of course, prudent to wait until the planet has reached its transit point of highest elevation in the sky.  In the early part of August this occurs early August, this occurs around 9.41pm (BST).

As the month progresses, nothing much changes as far as Saturn is concerned. By the 15th, the planet is still +0.3 mag and transits around sunset at 8.45pm (BST). Setting at just before 1am the following morning, this gives observers a reasonable window of time to study the ringed planet in all its glory. 

By the end of August, Saturn has diminished in brightness fractionally to +0.4 mag and now sets at around a quarter to midnight (from 51 degrees N).

Saturn's position, early evening, 15th August - Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

Uranus and Neptune

The outer gas giants are to be found, as usual, in Pisces and Aquarius respectively. Neptune, at a rather dim +7.8 mag, is the more early riser of the two, being further west in the ecliptic, and rises at just before 10 pm (BST) on the 1st. Uranus, at 5.8 mag, rises around an hour later.

On the morning of 10th August, the Waning Gibbous Moon slides to the south of Neptune in Aquarius by about 1 3/4 degrees, providing a handy signpost to the much fainter planet.  Three days later, on the morning of the 13th, the Moon passes to the south of Uranus by about 5 1/4 degrees.  

By the end of August, Neptune is a few days off Opposition in early September, though hasn’t changed significantly in brightness from the month’s beginning, though has increased diameter fractionally to 2.4 arc seconds.  Uranus is still a little under 7 weeks from Opposition in mid-October, but has increased in brightness by a little to +5.7 mag. 

While Uranus is technically a naked eye object, Neptune most definitely is not, though powerful binoculars and telescopes will show it relatively easily.  Given its maximum brightness and angular size this month - +7.8 mag and 2.4 arc seconds diameter, it can be likened to one of the brighter planetary nebulae in difficulty.  By way of contrast, M57, the Ring Nebula is +8.8 mag and 1.4 arc seconds diameter.  If you've located the Ring Nebula, Neptune will pose less observational difficulties, though admittedly is currently in a more barren area of the sky.

Uranus and Neptune in Pisces and Aquarius, August 2017 - Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,



Both Comets 2015 ER61 (PanSTARRS) and 2015 V2 (Johnson) have put on a good display over the past few months but are now both on the wane in terms of brightness.  2015 ER61 will intersect the Pleiades during the middle of August (15th-21st) and although faint at around the 13th magnitude, it should be interesting to see if you can pick is out in the predawn sky in Taurus.  

2015 ER61 within the Pleiades, 17th August 2017  - Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

2015 V2 is dropping through Centaurus during August - and as such is a very difficult object to observe from the northern hemisphere. At +8 mag and fading it is now long past its best, but readers in the southern hemisphere will now have a chance to see it better.

Happily for Comet hunters, there’s a new object not he horizon, the recently-discovered 2017 O1 (ASASSN1), which looks as if it could well put on quite a display over the rest of the year.  At time of writing, the ephemeris is still being worked out, but according to the BAA Comet Section it should be visible as at least a binocular object from early August, through the Autumn and Winter of 2017.  Watch this space…


Perseid Meteor Shower

It wouldn’t be August without the Perseid meteor shower, which actually run from mid-July to late August.  They will reach their peak on or around August 12th.  Last year’s shower peaked with a zenith hourly rate of around 150 meteors and this year is expected to put on a similar show.  However, the eternal nemesis of meteor observation, the Moon, will be around to spoil the party.  At Waxing Gibbous phase around the shower’s peak, the Moon will drown out many fainter meteors.  Yet there will be windows of opportunity in the early evening of the 12th and 13th to observe some early peak Perseids before moonrise occurs.  As ever, the opportunity to photograph the shower shouldn’t be neglected - just make sure the Moon isn’t in the field of view whilst attempting to capture the best of the Perseids.

Exploding Peseid over SW London, August 2015.  Image Credit: Kerin Smith

Photographic recording of the shower requires a regular DSLR, with a wide angle lens, set to a reasonably high ISO (800+)  - this will undoubtedly pick up at least a couple of bright examples of the Peseids during an evening's worth of timed exposures. Multiple exposures of 30 seconds-or-so, depending on your sky conditions will be more than adequate to pick up some Perseids over the space of a couple of hours - just make sure you have plenty of memory in your camera and that your batteries are fully charged prior to any attempt.


Deep Sky Delights In The Summer Triangle

 The Summer Triangle is an asterism that consists of the stars Vega, Deneb and Altair and was a term first associated with these stars by the Austrian astronomer Oswald Thomas in the early-to-mid 20th century, when he referred to it as Grosses Dreieck (Great Triangle) in the late 1920s and Sommerliches Dreieck (Summerly Triangle) in 1934.  This area of sky takes in the constellations of Cygnus, Lyra, Aquila, Vulpecula and Sagitta and contains some of the best deep sky objects in the whole sky.


The Summer Triangle and surrounding constellations.  Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

Starting from the most southerly tip of the Summer Triangle, we come to the major constellation of Aquila, The Eagle.  Despite its size and prominent position along the plane of there Milky Way, this constellation is curiously lacking in major Deep Sky objects.  The only one of great note is the interesting NGC 6741, otherwise known as The Phantom Streak.  This object is a planetary nebula of +11.69 mag and diminutive in size (as many planetaries are), at just 0.1 arc minutes across.  Looking like a ghostly parallelogram, the Phantom Streak is not an easy object, but its cocoon-like structure can be discerned by those with access to larger telescopes.  It is a rewarding find for those with the ability to find it.  The distance of NGC 6741 is not certain.  Some sources list it as lying 7000 light years distant, though others think it a closer object at around 5000 light years from us.  The Phantom Streak is notable for the possibility that its central star, a white dwarf remnant of a star much like the Sun, may be running out of hydrogen fuel and its dropping in luminosity.  This means the Phantom Streak may not be visible in its present form for much longer - a sign we live in a dynamic Universe.  Catch it while you can!

NGC 6741, The Phantom Streak.  Image Credit - NASA/ESA Hubble Space Telescope, Creative Commons

Moving up past Altair, we take a brief dog leg East into the tiny constellation of Delphinus, The Dolphin.  This lovely little collection of stars, though not especially bright, can easily be made out under dark conditions.  Delphinus' kite-shaped arrangement of four stars and the Dolphin's tail marked by the prominently blue Epsilon Delphini is unmistakable. 

Delphinus contains two globular clusters - nether particularly bright, but worth seeking out nonetheless.  NGC 6934 is the more Southerly and is found just under 11 degrees almost due east of Altair.  At +8.8 mag and 1.4 arc minutes in diameter it is hardly prominent, but is location in the rich star fields of the Milky Way go someway to explaining this.  Small telescopes show the cluster as a soft, rather indistinct ball of light, but larger instruments will be needed to show the scant detail it offers up to observers.  Lying over 50000 light years away, NGC 6934 was one of William Herschel's many discoveries - he first catalogued it in 1785.

NGC 6934. Image Credit: Hubble Image NASA/ESA, Public Domain.

Herschel also Discovered NGC 7006 which is located some 11 degrees to the NE of NGC 6934.  At +10.56, it is one of the fainter of our galaxy's globular clusters. This faintness is understandable when one considers NGC 7006's distance - an amazing 135,000 light years hence.  This cluster is described by various observers as quite comet like in appearance - a condensed central region and a halo of stars are not as distinct as they are in its neighbour. A very large telescope of 16+ inches aperture will be needed to resolve individual stars in this challenging target.

NGC 7006.  Image Credit: Hubble Image NASA/ESA, Public Domain.

Delphinus also contains a good planetary nebula:  the Blue Flash, or NGC 6905. This is more easily seen in small telescopes than either of the globular clusters previously mentioned.  Indeed, it is often overlooked, due to its proximity to the nearby M27 (more of which later), but the Blue Flash deserves more observation.  A blue-white ball of light, with extending lobes either side, NGC 6905 is +10.89 mag and  0.8 x 0.6 arcminutes in dimension and lies 2200 light years away.  Larger telescopes will start to pick up more of the object's uneven shape and central star.  It seems decidedly egg-shaped to some.

NGC 6905, The Blue Flash Nebula.  Image Credit - European Southern Observatory - Creative Commons

Just under 7 degrees to the west of The Blue Flash, over the border into Sagitta, The Arrow, sits another globular cluster - M71. 

Discovered in 1746 by Philippe Loys de Cheseaux, M71 is a very loose globular, which was perhaps understandably classed as an open cluster for a considerable amount of time.  Binoculars show it well, but smaller telescopes will start to resolve it into stars.  At 3.3 arcminutes diameter and +8.18 mag, M71 is a curious beast: its spectral makeup and spread of differing star types is much more suggestive of an open cluster, though observations of the radial velocities of its constituent stars have pointed to its globular nature.  It is thought to be particularly young for a globular cluster, being "only" 9 billion years of age.

M71.  Image Credit: Hubble Image NASA/ESA, Public Domain.

Moving further Westward, over the border into Vulpecula, The Fox, we come to one of the most celebrated clusters in the whole sky - Collinder 399, otherwise known as The Coathanger, for obvious reasons!  The asterism of The Coathanger contains ten bright stars, one of which is an orange-yellow colour, which contrasts nicely with the blue-white of the other nine.  A perennial binocular favourite, The Coathanger is a large object at 89 arc minutes diameter is best seen in widefield instruments at low powers.  Its unlikely appearance always raises a wry smile, as it is one of the sky's greatest practical jokes.

Chart showing the laocation of The Coathanger Asterism. Image created with SkySafari for Mac OS X, ©2010-2012 by Southern Stars,

From the ridiculous to the sublime, the next object is one of the best examples of its type in the entire firmament - M27, The Dumbell Nebula.  This planetary nebula is to be found 8 1/3 degrees to the east of The Coathanger and is a richly rewarding object to observe in any telescope.  Small telescopes show it as an elongated glowing box.  Larger apertures show more and more of the distinctive "apple core" shape.  Long duration exposure images show the whole object, including its ghostly outer layers, beautiful colours and complex internal structure.  The Dumbell is a true Messier object, as it was discovered by Charles Messier in 1764 and at about half the diameter of the Moon and +7.09 is easily one of the most prominent examples of its kind in the sky.


M27, The Dumbell Nubula.  Image Credit - Mark Blundell

We see M27 from the side on - hence its less-than-planetary shape.  Were we observing it from a polar viewpoint, it would appear ring-like.  But we are fortunate that the inner structure of the nebula is so well-defined from our perspective.  M27's distance is heavily debated, but now appears to be around 1200-1700 light years away.  Its age is thought to be relatively young - 3-4000 years-or-so.  It is an easy object to locate and should not be missed by any observer.

NGC 6885 is another inhabitant of Vulpecula and lies 4 2/3 degrees NE of the Dumbell.  It is a +8.10 open cluster, around 20 arc minutes in size.  Although not exceptionally bright, NGC 6885 is easily located in binoculars and is probably best-seen in a large pair.  This cluster contains over fifty member stars and has distance of around 1900 light years.

Eight and a half degrees NE of NGC 6885, across the border into Cygnus is the enchanting target of the Veil Nebula.  The Veil Complex – NGCs 6960, 6974, 6979, 6992 and 6995 in Cygnus is a famous Supernova remnant, spread out over six times the diameter of the Full Moon.  At combined brightness of +5 mag, The Veil can supposedly be glimpsed with the naked eye under truly exceptional conditions, but is much more likely to be seen (and better observed) in large binoculars and telescopes.  The veil lies underneath the wing of Cygnus, close to Gienah (Epsilon Cygni). The brightest section this nebula is NGC6960, otherwise known as The Witches’ Broom, due to its obvious broom-like shape, which reveals itself best in long duration exposures.  NGC6960 has the star 52 Cygni apparently buried within it (it is in fact at least 10 times nearer to us), making this part of the nebula an easier target to find with non-Goto scopes.  The Veil responds terrifically well to the OIII filter – indeed, it is almost the best-responding nebula to this particular narrowband wavelength.  This beautiful structure can be seen in all manner of telescopes, but large instruments with low power, widefield eyepieces present it spectacularly well.

NGC 6980 - Wester Veil Nebula, or Witches Broom.  Image Credit - Mark Blundell.

Drifting Westwards, past one of the finest double stars in the entire sky, the Creamy Yellow and Electric Blue of Albireo (Beta Cygnii), just across the border into Lyra, The Lyre, sit two notable objects, the first of whichis M56, which lies roughly equidistant between Albireo and Sulafat (Gamma Lyrae).  At +8.27, it is of similar brightness to  the aforementioned M71, though at 2.2 Arcminutes diameter – when compared to the larger M71 at 3.3 Arcminutes in size – is slightly more condensed and appears brighter.  Indeed, both objects would possibly appear more prominent were they not lying so close to the axis of our Galaxy and therefore obscured by parts of the Milky Way.

Roughly halfway between Sulafat and the neighbouring naked eye variable star, Sheliak (Beta Lyrae) sits one of the showpieces of the sky, the wonderful M57, the Ring Nebula.  M57's enduring popularity as a Deep Sky target may be partially down to the ease with which its location is to be found.  Looking like an elongated smoke ring drifting through space, the Ring Nebula is perhaps the archetype of all planetary nebulae.  Discovered in 1779 by the astronomer Antoine Darquier de Pellepoix, Messier was hot on his heels and independently discovered it a matter of days afterwards.  Rather disappointing in binoculars, yet easily spotted in most telescopes due to its comparatively high surface brightness, M57 takes magnification and filtration (especially the OIII filter) extremely well.  Naturally, the larger the telescope you point at it, the more the keen observer is likely to see, but those with smaller telescopes will not be disappointed as long as you keep magnification up. 

M57, The Ring Nebula, in detail. Image Credit: Hubble Image NASA/ESA, Public Domain.

M57's distance is still up for debate, modern estimates of the central star put it at about 1400-4000+ light years away - quite a variation!  It is thought is the former figure is the more correct, M57 is about a light year across from widest point to widest point and is a cylinder shape which we see from the end - quite the opposite, in fact, to M27's aspect.  It is thought that The Ring Nebula is around 5-8000 years old.

Back into Cygnus, climbing higher North up the spine of the Milky Way, we come to a reasonably diminutive, but nonetheless fascinating object:  NGC 6888, The Crescent Nebula. a bright, compact nebula, which is the expanding shell of a Wolf-Rayet Star (HD 192163), which is steadily shedding its outer layers.  The nebula glows due to the fact that it is gas is superheated by the collision of the boundary layer of a faster-moving inner solar wind, meeting a less energetic layer of solar wind formed when the gaseous layer of HD192163’s former outer atmosphere was ejected in its previous red giant phase.  This bow shock is about 25 light years across and appears to us as a crescent shape, glowing at +7.40 mag.  The "surface" of this crescent is incredibly detailed and its complicated texture can be noted in larger telescopes using OIII and UHC filtration.  Much beloved of Astrophotographers, the Crescent Nebula is a rewarding target for imagers.

NGC 6888, The Crescent Nebula.   Image Credit - Mark Blundell.

Right next door to the Crescent, clustered around the star Sadr (Gamma Cygni) is the vast expanse of the Gamma Cygni Nebula.  Glimpsed in large binoculars and telescopes from an appropriately dark locale, IC 1318, as it is otherwise known, is a huge patch of red nebulosity, slightly larger in dimensions than the Veil.  However, this nebula is very spread out, so its surface brightness is inherently low.  It is best visually isolated with H-Alpha Filters, but is more easily captured in long duration astrophotography.  The Gamma Cygni Nebula reaches out behind the Crescent and the star that is takes its name from.  Sadr is around 750 light years away, whereas estimates for the distance of the nebula vary wildly from 2000-5000 light years distance.

North America and Sadir Nebula, amongst Milky Way Star Clouds.  Image Credit - Kerin Smith

Further up the spine of Cygnus, just beyond its principal star, Deneb, is another vast nebula system: the North America Nebula (NGC7000) and tucked underneath it, the Pelican Nebula (IC5070).  Of the two, the North America is undoubtedly brighter (at +4 mag, compared to the Pelican’s +8 mag) and can be seen very well in large binoculars from a dark site.  An OIII or H-Beta filter can be used successfully to enhance NGC7000 in widefield telescopes, but the complex does not respond well to magnification. Both nebulae are part of the same gas cloud, which may be ionised by emissions from nearby Deneb.  If this is the case, their distance would be in the region of 1800+ light years away from our Solar System.

NGC 7000, The North America Nebula.  Image Credit - Mark Blundell.

Last but not least is a much smaller object, the Blinking Planetary or NGC 6826.  This nebula is 2.1 arc minutes in diameter and located towards Iota Cygni.  Dimensionally, NGC6826 is fractionally larger than the Ring Nebula and about the same brightness.  The "blinking" nature of this planetary is caused when an observer stares at the nebula’s central star, at medium to high power, this overwhelms the eye and the nebula fades from view.  When you look away to the nearby +8.5 magnitude star in the same field, the nebula reappears.  This is not a unique phenomenon and is noted in other compact planetary nebulae with prominent central stars, but is best seen in the Blinking Planetary.  Visually, the NGC6826 present two brighter regions on either side of its disc. These regions are Fast Low-Ionization Emission Regions or FLIERs for short.  These FLIERs are parts of the planetary formation which are expanding at extreme speeds in comparison to the surrounding nebula.  It is postulated that these areas are so dense that the ionising effect of the ultraviolet radiation emitted from the parent star cannot penetrate them.  The Blinking Planetary and the Saturn Nebula are two of the best known examples of planetaries that exhibit these FLIERs.

NGC 6826, The Blinking Planetary.  Image Credit: Hubble Image NASA/ESA, Public Domain.

Text - Kerin Smith