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M42


Tom2012

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Good evening everyone.

I was just thinking about Orion and wondered why it shows itself as green through the telescope? Just looked at some amazing pictures on here that people have done and there's reds, whites, silvers and everything. I know they are pretty long exposures but why, when looked at through a unfiltered scope with the naked eye, does it appear green?

Thanks everyone.

Tom.

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You are so lucky to see any color in any nebula. Most of us never see any color in any nebula and I suppose it's the condition of your eyes (health and genetics). But a lot of us do see a hint of color in some of the brighter nebulae when sky transparency is very good. The best Ive' seen M42 was with a 10" newt in very dark, transparent sky and I saw a hint of blue-green color.

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Hello Mr Q and Rory.

Really? So the colour of your eyes really does matter? I've got blue eyes and I'd never thought that'd make any difference. I understand the age barrier with pupils getting thinner as we age but I'd never thought colour would be a factor.

Thank you for replying.

Tom.

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Nothing to do with the colour of your eyes. It's to do with the way your eyes work in low light. Your eyes become more sensitive to movement than colour, employing different cells in your retina, coupled with a build up of light-sensitive rhodopsin (which is less sensitive to red light).

As a result, you'l be slightly more sensitive to the blue-green end of the spectrum than the red, which is why when you're dark adapted you see in almost monochrome, but green things like grass will appear light grey, but red things like a coke can will appear much darker.

I see m42 as green too. :)

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I agree with Tom and Nick. I was a little creeped out when I looked at M42 for the first time. There is definately something quite eerie about the way the trapezium is set in this very obvious dark band. As for colour, it looks fairly grey to me with maybe a little bit of green. I reckon I can see some red colour at the edges of M57 at low power though.

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The reason for the grey colour via the eye is that human vision defaults to black and white at low light levels. Rods and cones etc see http://hyperphysics....on/rodcone.html

Some slight colour might show in all sorts of objects if the light gathering power of the telescope gives sufficient output to stimulate colour vision. Other than colour vision problems I don't think that there is much variation in this from one person to another other than various types of colour blindness. Some people go through their entire life without knowing that they have marginal colour vision problems.

John

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WaneSoarer - I doubt you can see any color in M57 other than a bluish-gray tint on fairly high power (which I can with a 250mm newt in very dark skies). Though your scope may have a small amount of chromatic aberration, it should not be enough to see any color fringing around such an object. My avatar of M57 is from the Hubble and only with such a large mirror and view from space will images of the red in the nebula be seen. Maybe it was a trick of the eye in your case?

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  • 2 weeks later...

In my 5" Mak at low power (x60), I see it as a pale greenish lilac colour in direct vision. With averted vision, I am reasonably sure I also see (like Wavesoarer above) hints of reddish on occasion - usually before my eyes have fully adapted and gone more monochrome. The reddish may be a contrast effect of course.

Chris

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Back in February or March, me and my family went up to the Lowell Observatory where Pluto was discovered and the astronomers there set out two 10" and 8" Dobsonian telescopes and pointed the 10" at the Orion Nebula. I put my eye up to the eyepiece and peered at M42. The view was incomparable to anything I'd ever seen. It was like Hubble but in monochrome. I was the last in line so I got to stare at it for longer and I could see little hints of reddish-purple around the core and that was it. I have never seen color in it since. I actually have never seen color in any DSO's besides the Orion Nebula.

Josh

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