nobody special
sage
Reged: 12/30/08
Posts: 392
Loc: Connecticut
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There was a post in the beginner forum, a person using an XT8 scope just like mine who commented that he saw M42 as a grey cloud. I observed M42 quite a bit last winter and while my 80mm refractor always showed it as a grey cloud the 8" showed it as a green cloud, so I made the comment that he should have seen green in M42 when to my surprise some other posters mentioned that with even bigger scopes and darker skies couldnt see any color.
Why is this? I feel kinda stupid for making the statement I did in the begginer forum but to be honest I always see it as a green cloud,not on any special night but always. My wife, my buddy and even my kids have seen it as well.
Can anyone explain to me why this is? I want to understand this.
Keep in mind I live in red zone and still see it this way.
Thanks
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Tom
Orion XT8 Classic
Hyperion 13mm (With 28mm Tuning Ring)
Orion Sirius 25mm
Meade Series 4000 Plossls 32mm 6.4mm
Orion Shorty Plus 2x Barlow
Telrad
OPT OIII Filter
ND Moon Filter
80a Blue Filter
Smart Seat III
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NerfMonkey
sage
Reged: 06/12/08
Posts: 482
Loc: NE Ohio
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To me, from a red zone, it looks like a pale blue cloud with a seagull shape through my 15x70 binoculars. In the 12" Dob it has a much more obvious light blue color.
I don't know how long you've been observing or how many times you've seen it but the first few times I viewed it it looked like a bluish gray fuzzy patch. Now it looks like a huge blue cloud with incredible detail visible. So experience definitely plays a big part in what you see.
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Mike
Zhumell 12", Oberwerk 15x70s
107 Messiers, 247 total DSOs, 6 planets, 1 comet
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MikeRatcliff
Pooh-Bah
Reged: 06/12/04
Posts: 1327
Loc: Redlands, CA
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I'm one of those people who doesn't normally see color in M42, even in a 16" in dark skies or in light pollution.
But there was one time in the city with my 16" in terrible light pollution that it was distinctly green for me. Every other time there was nothing. Perhaps my eyes were rested or I ate a bunch of carrots that day.
I know my color vision threshold is not nearly as good as others who are looking through my scope. This weekend a group of us were looking at the Saturn Nebula that has prominent color. 3 people saw either green or blue or some combo, but to me the color was gray.
Yet there were two nights this past August in my light polluted skies that the Saturn nebula was as green as the green traffic stoplight, no doubt at all.
I have no explanation.
Mike
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16" f/4.9 dob, 1.25" Paracorr, 24 TV Widefield, 18 Circle T ortho, 13 Nagler T6, 12.5 UO ortho,
9 Circle T ortho, 2x TV Barlow 1.25"
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Hrundi
Pooh-Bah
Reged: 02/06/08
Posts: 1230
Loc: Estonia
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I don't see color in anything pretty much. Ring nebula looks grey, dumbell looks grey, m42 looks grey, blue snowball looks grey, saturn nebula looks grey, cat's eye looks grey.
12" scope, observe from pretty much pristine skies, although sealevel.
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Edited by Hrundi (10/19/09 07:36 PM)
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Dain
Carpal Tunnel
Reged: 03/24/05
Posts: 1596
Loc: N.Y. Adirondack Mnts. NGC 4565...
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I've always seen M42 as blue-ish-green...almost identical as teal. Of course because its so big I can see alot more of it, but this is pretty much the same color that I see when observing some planetaries as well. It's funny that many of us see it so differently. I'd like to know the science behind this as well.
Clear Skies to All!
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Best,
Dain
Adirondack Mountains (my true dark sky site)
@ Cedar River Flow
Local Site
Clear Skies?
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Bret Ford
sage
Reged: 07/15/07
Posts: 206
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Orion looks vividly green to me. I'm also curious about the science behind this. Is there an opthamologist in the house?
Bret
Quote:
I've always seen M42 as blue-ish-green...almost identical as teal. Of course because its so big I can see alot more of it, but this is pretty much the same color that I see when observing some planetaries as well. It's funny that many of us see it so differently. I'd like to know the science behind this as well.
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peter k
super member
Reged: 02/03/07
Posts: 172
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I definitely see green in moderate to large aperture under decent conditions. This thread sheds some (green) light on the optics of it: here
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joelimite
sage
Reged: 09/01/08
Posts: 234
Loc: Fayetteville, AR
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Looking through an 8" and a 3" inch scope, the Orion Nebula looks gray to me, with perhaps a tinge of blue. However, I've definitely heard of people seeing a green tint to it, and am curious about the science behind this as well.
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Orion XT8 Dob w/ Moonlite 2-speed Crayford focuser, Vixen A80MF w/ GSO 2-speed Crayford and Porta Mount
32mm Televue Plossl, 31mm Hyperion Aspheric, 24mm Meade SWA, 17,13,8mm Hyperions, 6,5,4mm TMB Planetary, 5mm Baader Genuine Ortho
Garrett Optical 20x80 UL Binoculars, Nikon Action Extreme 10x50 Binoculars
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Ptarmigan
Carpal Tunnel
Reged: 09/23/04
Posts: 2351
Loc: Arctic
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I always saw Orion Nebula with a bluish-gray with a greenish tint.
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Ptarmigans=Cute and Cuddly
Meade Starfinder 8
Nikon 10x50
Rebel XT
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 580
Loc: Northern Arizona
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Never really seen just how green it was until last Saturday night . Or Sunday morning . Very Green .
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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nobody special
sage
Reged: 12/30/08
Posts: 392
Loc: Connecticut
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Intresting.
Funny how four people viewing through my scope all see it as green.
While I never have seen M42 look anywhere near like the picture below the outer lighter green sections is the color I see.
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Tom
Orion XT8 Classic
Hyperion 13mm (With 28mm Tuning Ring)
Orion Sirius 25mm
Meade Series 4000 Plossls 32mm 6.4mm
Orion Shorty Plus 2x Barlow
Telrad
OPT OIII Filter
ND Moon Filter
80a Blue Filter
Smart Seat III
Edited by nobody special (10/19/09 09:59 PM)
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star drop
Guilty as Charged
Reged: 02/02/08
Posts: 16198
Loc: Snow Plop, WNY
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Years ago on a few transparent nights I was able to see the green and red in M42 easily using a 13.1" telescope in a red zone. Now with much darker skies using a 25" telescope the green is much more subdued. To me the colors have always been more evident at low magnifications. An increase in age of both myself and the mirror coatings may also be contributing factors.
The following is about my perception of yellow in a few deep sky objects. It may lay to rest the point mentioned about the eye / brain combination seeing green where there is red and red where there is green. I either see gray or distinct yellowish hues depending upon three things namely the objects true color (reddened by dust or otherwise), the objects brightness, and the aperture used for the observation.
Last year I did a little exercise after there was a similar question about seeing colors in globular clusters. One night I compared a few of the brighter globular clusters visible at roughly the same elevation above the horizon at the middle or end of spring I believe. The dimmer globular clusters had a grayish white tint while several of the brighter ones revealed distinct yellowish hues with M15 having the deepest yellow tint.
On another night the sky was very transparent and M32 looked like a yellow haze with a pinpoint nucleus in my 25". NGC 891 reveals no color to me in my telescope or a 28" telescope. But a recent view in a 32" telescope revealed a distinct yellowish cast. I am certain that the coatings on the 32" were newer than those on my telescope and that may have helped some.
The eyepieces used for these observations were 6-8 element designs in my telescope and six to nine element eyepieces along with a four element coma corrector in the 32".
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Ted
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Dain
Carpal Tunnel
Reged: 03/24/05
Posts: 1596
Loc: N.Y. Adirondack Mnts. NGC 4565...
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Tom,
Thats getting pretty close to what I see in the eyepiece of my long time 8-inch dob friend! If the green was toned down a bit in the hulk-ish colored sections, then all the teal-ish sections around it is what I see for pretty much the whole thing except maybe a very few slight variations of that color and where the core is massively bright. This object is one of the most unique objects in the sky to look at.
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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I only see M42 as a gray-green cloud in my 25". Bright, high surface brightness planetary nebuale, like NGC 7009, NGC 6543, etc, appear as a very emerald green though (at low power). A couple oddball planetary nebulae like IC 418 or Campbell's Hydrogen Star are actually rosey red, though, and that remains the only place in the sky I have seen true red.
Aperture won't really affect the apparent color of M42 past a certain point, becuase aperture is unable to affect surface brightness (assuming a constant exit pupil, which is more or less the correct assumption).
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
Edited by tatarjj (10/19/09 11:42 PM)
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Dain
Carpal Tunnel
Reged: 03/24/05
Posts: 1596
Loc: N.Y. Adirondack Mnts. NGC 4565...
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Quote:
I only see M42 as a gray-green cloud in my 25". Bright, high surface brightness planetary nebuale, like NGC 7009, NGC 6543, etc, appear as a very emerald green though (at low power).
I also see certain planetaries as an emerald green as well at low power in my 8-inch dob. I'm assuming this is the same teal-ish color I'm seeing in M42, but since the area of light is much smaller and focused, it makes the color appear brighter thus making it the emerald green color?
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Best,
Dain
Adirondack Mountains (my true dark sky site)
@ Cedar River Flow
Local Site
Clear Skies?
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
I also see certain planetaries as an emerald green as well at low power in my 8-inch dob. I'm assuming this is the same teal-ish color I'm seeing in M42, but since the area of light is much smaller and focused, it makes the color appear brighter thus making it the emerald green color?
I think that's the primary factor- PN has higher surface brightness, so you can perceive the color easier. However, there may be another factor, but I'm only speculating here- perhaps M42 has more hydrogen alpha emission than your typical planetary. Hydrogen alpha is, of course, red, which would cancel out (well, brown out) some of the green in M42 if your eyes were perceiving any of the red at all. However, to counter that, M42 DOES have more hydrogen BETA (another green hue) than a typical planetary. In the end, you shouldn't ONLY consider surface brightness when asking why small, bright planetary nebulae look so much greener than M42, you also have to consider the spectral content of the light.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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drshr
professor emeritus
Reged: 06/09/08
Posts: 673
Loc: Darwin, Australia
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I have only ever seen it as green. I thought everybody else also saw it as green until I read this thread!
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Doc
14" F5 DOB.
APM 8" F6 Achro.
APM 105mm F6.2 CF APO.
120/F8.3
150/F5
80/F6.25ED
25x100 Binos.
To affect the quality of the day, that is the highest of arts.
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 530
Loc: Haren, The Netherlands, Europe
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In the 55mm I see M42 as pale green under very dark and clear country skies. The color is strongest at 3-4mm (largest I can get with 1 1/4") exit pupils, then fades into grey at round 1mm exit pupil. In my Questar 7, I see M42 as very vivid green even at 1.5-2mm exit pupils (32 and 24mm Brandon) from my backyard.
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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rocco13
Got Milk?
Reged: 07/29/06
Posts: 2642
Loc: Phoenix, Arizona
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Quote:
I don't see color in anything pretty much. Ring nebula looks grey, dumbell looks grey, m42 looks grey, blue snowball looks grey, saturn nebula looks grey, cat's eye looks grey.
I'm also one of those who rarely see color in DSOs, although M42 does appear to have a slight greenish hue, and there are a few PNs which appear bluish to me...Ghost of Jupiter, Catseye, Saturn Nebula, Blue Snowball.
But everything else is just gray to me.
One odd thing for me...in my C8, Uranus and Neptune are definitely blue (or blue/green), but in my Z12 they actually appear yellowish, which made me doublecheck my charts to make sure I was looking at the right object. Uranus is easily a disk, Neptune a little harder to discern as a disk, but once confirmed, I was surprised at the color. 
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Rocco
Zhumell Z12
Super C8 (1984 vintage)
Celestron 102 f/5
and a cheap pair of binoculars
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
I always saw Orion Nebula with a bluish-gray with a greenish tint.
Well, the science is pretty clear, emission nebulae emit alot of green (oxygen III and hydrogen beta) light and red light (hydrogen alpha). Because our eyes are insensitive to red, especially at low light levels, for the most part all we see is the green oxygen III and hydrogen beta. Very high surface brightness planetary nebulae should appear especially green, and to many observers such as myself, they do. Their high surface brightness allows the perception of color easier, AND they emit a higher proportion of green oxygen III than regular emission nebulae.
Where the science is not clear to me is how so many people perceive planetary nebulae as blue. As far as I know, there is no blue emission component- certainly not a strong one. Furthermore, our eyes are much more sensitive to green than blue, so since there is such a strong green component, you should not see blue at all. I would suspect that its a defect in many people's color sensing ability. Perhaps age plays as part in it, as color sensitivies change as you get older and so many people involved in astronomy are older folks, but I don't know. It would be a good survey question/poll to put up- age vs. what color you see planetary nebulae as.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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