Dark sites - what have you seen, that you couldn't at home?

[Flame Nebula]

Hi, assuming you don't live in pitch black, what have you seen at dark sites that you couldn't at home. And what would the equivalent aperture increase be, if that makes sense? So, e.g. 5 inches at dark sire equates to 8 inches at home(assuming not dark) . Not sure I'm making it clear, but hope you get my meaning. 

[bosun21]

When I visit the Scottish Highlands and Islands each year which is Bortle 1-2 depending on where i holiday the skies when clear can be overwhelming. The sheer number of stars in the sky is amazing and sometimes throws me when trying to get my orientation in the sky. The difference is not like between a 5" and an 8" at home. You don't truly appreciate a dark sky until you experience it for real. I  have only taken scopes up to 6" when I travel due to weight etc. I look forward to my trips every year. Only if the clouds played ball more often.

[Flame Nebula]

8 minutes ago, bosun21 said:

When I visit the Scottish Highlands and Islands each year which is Bortle 1-2 depending on where i holiday the skies when clear can be overwhelming. The sheer number of stars in the sky is amazing and sometimes throws me when trying to get my orientation in the sky. The difference is not like between a 5" and an 8" at home. You don't truly appreciate a dark sky until you experience it for real. I  have only taken scopes up to 6" when I travel due to weight etc. I look forward to my trips every year. Only if the clouds played ball more often.

I remember going to a wedding reception in Derbyshire many years ago, and we had to walk down a path with no lighting in some kind of tree'd path and I couldn't see my hand in front of me, but when I looked up, it was like "Wow!" I'm not sure my family were as amazed as me, but it looked like someone had thrown a bag of icing sugar across the sky! Beautiful. I'd love to live somewhere like that, but in easy reach of all facilities of course😉

Edited March 20 by Flame Nebula

[Elp]

 

12 minutes ago, bosun21 said:

You don't truly appreciate a dark sky until you experience it for real

I've seen this in Asia, complete rural, blackout, no light sources other than starlight. It's like those Pixar night skies you see in their films just ebbs and flows of stars everywhere, and this was over 20 years ago. Don't think I'll ever experience this again (eyes would have been better back then too).

[Cosmic Geoff]

Dark skies are amazing - as the others say above.  Not easily compared with an urban area.  With an 8" SCT, looking for galaxies from home was unrewarding, but at my sister's place in Devon one year I was using a galaxy list in the GoTo and logging fainter and fainter ones till I ran out of energy. 

However, I imaged one particular galaxy field from home with my 4" f5 refractor, that I'd seen in Devon with the 8" SCT, and I imaged all the same faint galaxies.

[Roy Challen]

I live in a large town centre, so pretty much any DSO is invisible to me. However, I go to Kazakhstan regularly and on one visit a few years ago, we went to a place that is truly remote. Such places ought to be Bortle 0. The Milky Way looks like thick cloud, you cannot clearly see constellations for the stars, and DSOs are no longer faint fuzzies! I saw the dust lane in M82 through 12x50 bins, with ease. Unforgettable.

[NGC 1502]

There’s no doubt that a dark site is very rewarding to visit.

But to answer your question as to what I’ve seen from a dark site that I couldn’t see from home…

From my light polluted back yard in a large town many deep sky objects can be observed that are better seen under a darker sky.  It’s not that many DSO’s are invisible from home it’s that they come alive at a dark site.

From home the least affected DSO’s are double and multiple stars. So my recommendation is to enjoy what you can wherever you observe from. Don’t let light pollution rob you of your enjoyment. Make the best of what you have rather than pining for what you don’t have.

It’s the old but true saying, “Is your glass half full or half empty?”.

 

[PeterStudz]

I have been to a Bortle 1-2 site. There is  no way that aperture can make up for it as under light pollution an increase in aperture also increases the background skyglow. 

As @bosun21 mentions - there are so many stars and so many bright stars that it’s hard to get orientation. Eg even Saturn was lost and took me time to locate. The Milky Way so bright that it cast a reflection on the water. I could see the Swan Nebula naked eye (I can’t even see that in my 8” Dob from my Bortle 7 garden). All I had was a small 4.5” newt on a wobbly tripod but the Triffid Nebula really bright and wonderful. The Lagoon Nebula was stunning and hard to take my eye away from the eyepiece - better than any photograph. 

[Flame Nebula]

2 hours ago, Roy Challen said:

I live in a large town centre, so pretty much any DSO is invisible to me. However, I go to Kazakhstan regularly and on one visit a few years ago, we went to a place that is truly remote. Such places ought to be Bortle 0. The Milky Way looks like thick cloud, you cannot clearly see constellations for the stars, and DSOs are no longer faint fuzzies! I saw the dust lane in M82 through 12x50 bins, with ease. Unforgettable.

Hi Roy, 

I found your message almost poetic. 👍

It makes you wonder, what would that sky have looked like through the eyes of a cat? 

I must try and get to some really dark sites more often. Even in the midlands I have witnessed them. 

Mark

[Flame Nebula]

27 minutes ago, PeterStudz said:

I have been to a Bortle 1-2 site. There is  no way that aperture can make up for it as under light pollution an increase in aperture also increases the background skyglow. 

As @bosun21 mentions - there are so many stars and so many bright stars that it’s hard to get orientation. Eg even Saturn was lost and took me time to locate. The Milky Way so bright that it cast a reflection on the water. I could see the Swan Nebula naked eye (I can’t even see that in my 8” Dob from my Bortle 7 garden). All I had was a small 4.5” newt on a wobbly tripod but the Triffid Nebula really bright and wonderful. The Lagoon Nebula was stunning and hard to take my eye away from the eyepiece - better than any photograph. 

Hi Peter, 

Amazing! The milky way cast a reflection on the water! 

These stories make you realise that we are living inside a galaxy with billions of stars! 

Mark

[Martin Meredith]

As others have said, well away from light pollution (hard to call them 'dark' skies as they're bright with stars) it is hard to get one's bearings at first, as the familiar constellations are buried within larger patterns. Some of the objects that are hard to appreciate under light pollution with the naked eye become prominent. I think it was Melotte 111, a large open cluster in Coma, that really caught my eye when I was lucky enough to experience really good skies in Capitol Reef NP in Utah in spring some years ago.

 

[Flame Nebula]

20 minutes ago, Flame Nebula said:

Hi Peter, 

Amazing! The milky way cast a reflection on the water! 

These stories make you realise that we are living inside a galaxy with billions of stars! 

Mark

I had to look into this milky way thing further, and found loads of stories on CN from people who'd had seen the milky way cast shadows! But apparently also Mars,(at opposition) Venus and Jupiter can too! Incredible. 

[Stu]

If you are not familiar with the concept of surface brightness, it is worth reading up on to understand object visibility better. Apologies if you know all this already but hopefully it will help others if not you.

Objects have a magnitude, but they also have an area. In the case of a star this is effectively the size of the airy disk, so the light is highly concentrated, but planetary nebulae, globular clusters, galaxies and supernova remnants all have a size and area; the light in them is spread out over that area. Think of it like a torch with a variable beam. At its narrowest setting, the light is bright and concentrated, on its widest, it is spread out and much fainter. The same applies to deep sky objects.

The other thing to note is that the sky itself has a surface brightness, which varies depending on light pollution and the Moon phase etc. If there is sufficient difference (contrast) between the object and the sky background then you see the object, if not then you don’t. It is a complex area though so this is a simplistic summary of it. Sky transparency also plays a large role in faint object visibility.

So, the easiest objects to see are often the planetary nebulae and globular clusters which are smaller and brighter. The trickier are faint small galaxies with low surface brightness. The Veil and North America Nebula are examples of large faint objects which need a dark sky to see.

M31 is a bit of a mix in that its core has high surface brightness and the spiral arms very low surface brightness. The core can be seen even from quite heavily light polluted skies so it seems quite small, but under very dark skies with binoculars or a widefield scope, you really start to see how huge it is.

Contrast for some objects like planetary nebulae and supernova remnants which are formed from ionised gas and emit light in certain frequencies can be improved by using narrowband filters such as UHC or OIII. Galaxies however emit light across the spectrum so the only real way to improve the views is to go to dark sites.

So, after much rambling….. objects not seen under home skies but seen under dark skies…. When I lived near London (Walton-on-Thames), I could never see M101, M33 or M51, all relatively low surface brightness galaxies or M1 which is SN remnant. Now I am in Somerset, although my skies are not amazing they are still a lot darker and I can see these objects, although 101 and 33 need good transparency.

As for small scopes performing better under dark skies…. The best example was taking a 66mm refractor to Tanzania on Safari where I saw objects I could not see from home in an 8”. Those were Bortle 1 skies though. The worst thing was it was an open camp so I was too worried about being eaten to get the best out of the skies! I’ve had many good times with small scopes from 60mm to 100mm under dark skies in the UK and abroad and it is always worth making the effort.

[Ratlet]

I'm blessed with dark skies and awful eyesight even with glasses so I don't see too many stars without the scope, but I get to see lots of objects that are considered faint.  The veil was a particular pleasure.  Without a filter it was more a textural difference than anything.   Like when carpet is brushed in different directions.  M51 is marvelous.

Still not seen any detail in M31 though.

Surface brightness is one of those things that I can wrap my head almost around (if I consider object and sky brightness separately) but I could feel my brain dribble out my ear when I tried to understand how magnification affects how the difference between the two is perceived by the brain.

[John]

Quite a few years back now I went to an SGL star party which was held near Hereford.

I had a 6 inch mak-newtonian with me on that trip and we had a couple of really dark nights. My friend Mark and I had a memorable night chasing galaxies with our 6 inch scopes (he had a Skywatcher 150 F/5 with him I recall). 

On that trip I reckon my 6 inch scope was showing DSO views as well as my 10 inch could on a dark night at home. 

That said, I have seen the Horsehead Nebula a couple of times from my back garden so I do occasionally get really, really good nights here as well.

 

Edited March 21 by John

[Flame Nebula]

1 hour ago, Stu said:

If you are not familiar with the concept of surface brightness, it is worth reading up on to understand object visibility better. Apologies if you know all this already but hopefully it will help others if not you.

Objects have a magnitude, but they also have an area. In the case of a star this is effectively the size of the airy disk, so the light is highly concentrated, but planetary nebulae, globular clusters, galaxies and supernova remnants all have a size and area; the light in them is spread out over that area. Think of it like a torch with a variable beam. At its narrowest setting, the light is bright and concentrated, on its widest, it is spread out and much fainter. The same applies to deep sky objects.

The other thing to note is that the sky itself has a surface brightness, which varies depending on light pollution and the Moon phase etc. If there is sufficient difference (contrast) between the object and the sky background then you see the object, if not then you don’t. It is a complex area though so this is a simplistic summary of it. Sky transparency also plays a large role in faint object visibility.

So, the easiest objects to see are often the planetary nebulae and globular clusters which are smaller and brighter. The trickier are faint small galaxies with low surface brightness. The Veil and North America Nebula are examples of large faint objects which need a dark sky to see.

M31 is a bit of a mix in that its core has high surface brightness and the spiral arms very low surface brightness. The core can be seen even from quite heavily light polluted skies so it seems quite small, but under very dark skies with binoculars or a widefield scope, you really start to see how huge it is.

Contrast for some objects like planetary nebulae and supernova remnants which are formed from ionised gas and emit light in certain frequencies can be improved by using narrowband filters such as UHC or OIII. Galaxies however emit light across the spectrum so the only real way to improve the views is to go to dark sites.

So, after much rambling….. objects not seen under home skies but seen under dark skies…. When I lived near London (Walton-on-Thames), I could never see M101, M33 or M51, all relatively low surface brightness galaxies or M1 which is SN remnant. Now I am in Somerset, although my skies are not amazing they are still a lot darker and I can see these objects, although 101 and 33 need good transparency.

As for small scopes performing better under dark skies…. The best example was taking a 66mm refractor to Tanzania on Safari where I saw objects I could not see from home in an 8”. Those were Bortle 1 skies though. The worst thing was it was an open camp so I was too worried about being eaten to get the best out of the skies! I’ve had many good times with small scopes from 60mm to 100mm under dark skies in the UK and abroad and it is always worth making the effort.

Thanks Stu! 🙂

[Flame Nebula]

10 minutes ago, John said:

Quite a few years back now I went to an SGL star party which was held near Hereford.

I had a 6 inch mak-newtonian with me on that trip and we had a couple of really dark nights. My friend Mark and I had a memorable night chasing galaxies with our 6 inch scopes (he had a Skywatcher 150 F/5 with him I recall). 

On that trip I reckon my 6 inch scope was showing DSO views as well as my 10 inch could on a dark night at home. 

That said, I have seen the Horsehead Nebula a couple of times from my back garden so I do occasionally get really, really good nights here as well.

 

Thanks John. Was that with your 12 inch dobsonian? 

[Mark at Beaufort]

14 minutes ago, Flame Nebula said:

Thanks John. Was that with your 12 inch dobsonian? 

No John had his 6" mak-newt and I had a 6" Skywatcher 150 f/5 Newt. We must have seen 30+ galaxies - such a memorable night.

[Flame Nebula]

36 minutes ago, Mark at Beaufort said:

No John had his 6" mak-newt and I had a 6" Skywatcher 150 f/5 Newt. We must have seen 30+ galaxies - such a memorable night.

Sorry, I meant did he see the horsehead nebula with his 12" dobsonian, when he saw it at his home. 

Edited March 21 by Flame Nebula

[Highburymark]

30 years ago when I was a journalist I was lucky enough to go on a trip to Yemen in southern Arabia. One night we drove for several hours into the desert to the east - an area which has the fitting name: the Empty Quarter. Definitely the darkest skies I’ve experienced, though sadly without a telescope. The best skies I’ve seen in Europe were off the southern coast of Crete. But at home in north London, the number of Messiers I can see from my garden can be counted on one hand. 

[Stu]

Talking of SGL star parties, at SGL10, I had a 16” dob and we had four clear nights including a couple with good transparency. I must have seen fifty or sixty galaxies that weekend. I had a push to system which really helped keep track of where I was and in identifying what I was looking at. Trawling around the Virgo cluster and getting ten plus galaxies of Markarian’s Chain in the field of view at once was fab.

A few reports below which may be of interest.
 

 

[ollypenrice]

I moved from Derbyshire to a deliberately-chosen dark site in the part of France identified as the best by professional astronomers' site-surveys going back to the thirties. I wouldn't know where to start, really, in making a comparison. In Derbyshire I never saw M101 at all.  Here I see it in a budget finderscope. I could never see the Rosette, with or without filter. Here I can see it either way in anything between binoculars and a 20 inch. I've seen the Gegenshein, naked eye, here but, on the other hand, I've never seen M33 unaided.

While both visual and photographic astronomy are outstanding, here, they both take second place to the simple fact of living under an unpolluted sky. Even if we're just driving back from a restaurant, or I'm nipping out to fetch some firewood, the night is night, it's dark and starry. It feels like the difference between breathing exhaust fumes and oxygen.

Olly

[John]

3 hours ago, Flame Nebula said:

Thanks John. Was that with your 12 inch dobsonian? 

Yes, my 12 inch dob. Hardest thing I've ever observed I think.

Easy for the EEVA users though 😉

[Beulah]

My rough calculation is an increase of 2 inches of aperture for 1 Bortle reduction

For example, a 12 inch telescope in a Bortle 4 sky is more like a 14 inch telescope in a Bortle 3 sky...

[Bugdozer]

10 hours ago, Flame Nebula said:

I had to look into this milky way thing further, and found loads of stories on CN from people who'd had seen the milky way cast shadows! But apparently also Mars,(at opposition) Venus and Jupiter can too! Incredible. 

This is one thing that I am always curious about when people talk about really dark skies and the descriptions of them given in the Bortle classifications, because some of it doesn't quite make sense to me. 

Firstly, a higher Bortle sky is always going to have more light from the sky overall than a lower Bortle sky. No objects actually lose brightness under a high Bortle sky, they just lose contrast against the increasingly bright background glow that is everywhere, until at some point they are effectively rendered invisible. But their light IS still coming down. 

However, in my experience, once you get down to about Bortle 2.5, there isn't actually enough light to see any shadows at all. The Milky Way could be right overhead, and clear to look at, but I can't distinguish between looking at the ground and having my eyes shut. Basically, the amount of light given off by things like the Milky Way is below the threshold at which my eyes can detect reflected light from objects. I can believe something like Venus could give off enough light to cast a shadow at its brightest, but if I already can't see the ground at all, then having an even darker sky is not going to make shadows on it more visible. Seeing it reflected off water makes sense, but I am dubious of darker skies seeming to make our eyes more sensitive to light which is already below detection threshold.