Colour in the Orion Nebula?

[Astro78]

Last night after a patient wait for the Orion Nebula to rise into view (not good here in the east), I'm quite sure i could just make out pale blue/green (mostly pale green) through the 32mm TV.

This from Sydney and with an 8" Newt. With averted vision I'm 99% sure, 1% very tired and dreaming. The photos (in google) show red, no green!

Could there be other factors at play here, besides lack of sleep?

When switching to the 15mm LV there was more detail, but just grey. Back to the 32 and there it was...

[ballaratdragons]

Yep, some colour can be seen in Orion Nebula,

but an 8" and from Sydney :eyepop:
That's 2 things that go against it.

I use a 12" in very dark country sky to see the colour of Orion neb, but the clubs 8" can't see it. Even with our dark sky!

Your eyes must be very sensitive!!!!!! :thumbsup:

As far as colour, some people say they see it in pale pink, some say pale green.

I personally (in dark skies) see both colours in Orion neb. Not bright, but very pale pastel colours.

[Rodstar]

Yes, from from what I have heard from various observers over the years, different peoples' eyes have varying levels of sensitivity to colour. Also, sometimes over time with training we can become a bit more aware of colour.

In my first season of observing with a 10 inch scope, I did not notice any colour in M42 at all, only grey. Then, the next summer, the green suddenly became quite obvious in the same scope, although it was only quite pale in appearance. Thereafter, the colour was immediately obvious everytime I observed, even through scopes of 8 inches aperture.

I now observe with 20 inches, and I see, with direct vision, an emerald green in the central region of M42, pinks in the mid to outer regions, and even some peachy tones in particularly still conditions at the far outer regions. Remarkably, some other observers, looking through the same 20 inches, cannot detect the colour at all, or only see it very faintly. Most only see the green, and no pink at all.

Over winter I had the pleasure of seeing some pink hues in M8. It was quite subtle, but there, nonetheless. Many planetaries show very obvious colour, even in smaller scopes, generally they are pale aqua.

I too wonder sometimes if I am seeing what I want to see in M42, but then I compare what I see with other experienced observers, and we describe the same thing, always with the green in the central region and pinks at the edges, which is quite different to the images one sees on this forum, and elsewhere, where, as you say, there is no green.

I understand that green is the colour our eyes are most sensitive to, so we tend to sense that first.

[Astro78]

Thanks for your responses guys.

Can't wait to see Orion through a bigger scope and away from the city one day. It sounds amazing, what am I saying it's amazing from here!

All the extra beta carotene in the diet might be paying off :thumbsup:

[ballaratdragons]

:lol: Eat more carrots and tell us if you can see colour in distant galaxies!

Wouldn't that be a buzz!!!! :eyepop:

[StarLane]

I've noticed pale greens(mostly) and blues right from the first time I viewed it. Orion M42 was the first neb I viewed when I purchased my 10inch, it blew me away. Because it's so bright(compared with all other nebs), our eyes can see some colour. With dull objects we can only see greys. It's all to do with the rods and cones on our retina. Film and CCD cameras are alot more sensitive compared to what we see with the naked eye or even averted vision. We see these colours in M42 because it's bright, with a large aperture scope, the colour would be even better.

[Astro78]

I think you must be referring to the 'mushrooms' for that one Ken :P

So if Orion is the brightest nebula, whats the next couple in the list?

[ngcles]

Hi Trav & All,

I'm not surprised by your report at all Trav. I could certainly see lime green colouration in M42 with my old 8" with no difficullty 15-20 years ago when I was in my 30s. It was as you say easy to see at low power and even in a suburban site with a ZLM about +4.9. Less convincing at mod to high powers. But that was the only colour I saw.

At low light levels,we see greens first and most easily because the colour receptors in your eyes are most sensitive to light in the middle of the visible light spectrum -- ie yellow-greens.

The 10" ditto but a more saturated lime green.

When I got the 12" I wasn't expecting to see any other colour but was taken by surprise (I expected "other" colours would only kick in at 16" and above) when I started to see faint blues along the "wings" of M42 and very occasional dirty pinks elsewhere but only in a true dark sky.

With 18", the lime green colour is visible while observing even in the Sydney CBD at Sydney Observatory. At a dark site the lime green is overpowering with bluish overtones in the "wings" and dull sorta pinky-russet away from the very brightest portions and areas close by the wings and elsewhere. Easier and easier in 24".

No one has mentioned nearby M43, but on a couple of occasions in excellent condiitions with the 18", the whole of M43 has looked a dull browny-red which I found quite strange as it is has comparitively low surface brightness -- _compared to_ M42.

Only on very good nights with the 18" does Eta Carinae (NGC 3372) have any very faint lime colouration in the very brightest parts.

The Tarantula (NGC 2070) is distinctly bluish from 10" and up at least with the colour intensifying with aperture. M17 also shows a distinct lime green in 10" and up. M8 is also a somewhat fainter lime green in 10" and up.

Colour in these non-stellar objects is tremendously subjective and as others have noted is dependent on the experience level of the observer -- your perceptons of what to look for and what to expect are important. Jupiter is a good example of this. At Sydney Observatory, many people cannot see any colour in Jupiter's cloud bands until I tell them what to look for and where -- then all of a sudden they see it. Same for the greenish tinge to the albedo features on Mars (they only look green because of contrast with the otherwise apricot pink areas). Many novices see them as simple grey until their experience at the eyepiece grows.

Interestingly, I believe David Malin continues to contend that it is not possible at all to see colour in M42. He only sees it as grey and denies colour is detectable in the human eye at that light level. Hmmm ...

The overwhelming majority of amateurs beg to disagree I think. The younger the observer, the easier it is to see colour. I speculate this is because of yellowing of the cornea as we get older from U.V.

_Wear those U.V resistant sunglasses religiously folks_! Mine are almost welded on for that reason -- also cataracts run in my family.

Best,

Les D

[Rodstar]

Les, it is fascinating to hear about the differences in people's colour perception.

Whereas you see a yellow/green or limey green, I see an emerald green. I wonder what that is about??!!

Also, I don't seem to pick up the blue colouring that you speak of....I have never perceived any colour in the Tarantula, but now that you have mentioned it, I will study it closely if these clouds ever clear.

With M42, I have heard other observers talking about seeing a bluish-green, but I have never sensed any blue at all in that object.

I have not seen colour in M17, but will make sure I have a good look next winter.

[Astro78]

G'day Les and party,

What an awesome reply! The notebook has now filled up several more pages (Thank you)- :thumbsup:

Woke up this morning praying the scope had grown a few inches. Nope.

Around 1am last night the clouds had cleared so with no cool down time I set up and dragged the girlfriend out to have a look at Orion - she could see the pale green too (she's telling me now more bluey than green??-will get a re-check next clear night though). What's amazing is she has quite average eyesight. A couple of years younger than I, further proving the age theory.

I believe to have read somewhere that the TV eyepieces exhibit a bit of green when compared to the Pentax if recalling correctly. The Pentax being the truest colour... What EP's are you guys using on the low power?

Spent half a night on the Tarrantula a little while back, missed the blue with the 8" but hanging for another try.

Surely the full 27mm field stop lit up to 100% is another factor?? Les?

PS: The 'Mary Rose' looks impressive Rod!

[asterix]

Here's the scientific explanation of colour in M42 and the like (I'm an optometrist).

Our eyes have rods and cones. Rods are used for lower light levels and only see shades of grey. They have their highest concentration slightly away from the centre of our vision - hence why averted vision worked to see things in low illumination.

Cones are used for bright illumination and allow us to see colour as there are 3 types. Cones have their greatest concentration in the centre of our vision, and we are most sensitive to green wavelengths. So to see colour you need to look directly at the object, and if its bright enough to register with the cones your will see green then red colours if present. The object needs to be brighter to see the red as we are less sensitive to red wavelengths than green.

Cameras/CCD/film are more sensitive to red light hence M42 looks red on photos.

[ballaratdragons]

. . and how stuffed our eyes are!

I am able to see minutely fine detail in Galaxies, yet I have what is called 'night blindness'! :shrug:

I can't see in near dark!

[Rodstar]

Well I studied the Tarantula very carefully last night for a good 15 minutes, and through the 20 inches I did not detect even a hint of any colour....grey grey grey. Will keep trying.

[jjjnettie]

I see shades of green and pinkishness in M42.
Using the same ocular I see only greyscale in the Tarantula.
I've not really looked for colour in the Eta Carina nebula yet, I'm too busy being awestruck by it's overall glory to notice. But I'll put it on my observing list for next time the clouds clear.

[AJames]

I have been reading the descriptions about the colour of the Orion Nebula here with some interest.
Attached is an image of the Orion Nebula, which to my eyes seems about colour that I see. The difficulty for the image here, however, is also showing the true luminosity of the gas, which in the telescope seems more lightly pearly white or "grey" than any kind of green.
Those wishing to see the "grade" of the colour might find it best to try and put the nebula and stars slightly out of focus. This will makes the green colour more washed out near the edges of the nebula, while the light around the central trapezium is a much lighter green or whiter or "greyness."

Note: I have an article on the history of the "Orion Nebula" on my website, which was only recently updated, and this might be of interest to the curious on this grand nebula of the sky. http://homepage.mac.com/andjames/Page204.htm

As to the Tarantula Nebula or even Eta Carinae, I also see not visual colours - the latter (Eta Car) appears merely as pearly white, which I think is just because the light spread over a much wider area.

Regards,
Andrew

IMPORTANT NOTE : "Grey" is an impossible in stellar objects or nebula, as all have light that is chromatic - composed of multiple saturated colours as we seen in spectra or as hues. There is no black or white (grey) scale with any such objects. Ie. The heavens are not like black and white photography.
So-called “acromatic colours” in painting and art are regarded as achromatic or neutral, but whether white or black are colours is open to debate. White light is in reality is NOT defined as a colour because it compromises the sum of all the radiations of the perceived visible spectrum. With light there are no mixtures of black and white in starlight or sunlight, so what we are really describing is a montage of monochromatic hues.
This is far different from the artistic view of colours in the world. What the eye visually sees cannot be adequately described in these terms - a fault with the persistence of the early ideas of colour. (It is also a failure of certain untenable colour descriptors often wrongly used by observers.)

There is absolutely no need, therefore, to describe colour in terms of tone, value or purity OR even for “lightness” (grayness). There is only hue and saturation in starlight and sunlight.

“Greyness” is decribed in and white photography as chiaroscuro (white-black-grey). The term is also used in the describing the treatment of light and shade in pencil or charcoal drawings and painting. This Italian word comes two words chiaro - bright and clear and oscuro meaning obscure and dark. (In Latin, clarus & obscurus, also an Italian oxymoron!)