Talk:Orion Nebula

10 degree diameter??
The "Structure" section gives this number, which would make the nebula large compared to Orion itself. Perhaps 10 minutes is intended? —Preceding unsigned comment


 * I checked many other sources and the author likely intended 1 degree. I will edit the text to reflect the correct extent. Even the article detail table shows it as 1 degree. Jascal (talk) 04:27, 4 March 2012 (UTC)

Apparently the actual invisible halo around the core nebula is really big JdelaF (talk) 06:44, 27 March 2022 (UTC)

Visible to the naked eye
Perhaps include a photograph highlighting this Nebula being viewed from earth? Eddie mars (talk) 18:29, 2 March 2010 (UTC)

Speed
I am not an astronomer by any means, but I think I would perhaps take issue with the sentence in the second paragraph which reads "There are also supersonic "bullets" of gas piercing through the dense hydrogen clouds of the Orion Nebula". Does the concept of 'supersonic' really have any meaning at interstellar densities (a few million particles per cubic metre at best)? Perhaps 'fast-moving' with an estimate of the relative velocity might be better? —Preceding unsigned comment added by 77.107.162.102 (talk) 10:01, 4 March 2009 (UTC)


 * No, "supersonic" really is meaningful in this context. Any fluid medium, no matter how low its density, has a characteristic speed at which pressure waves propagate through it that depends on both that density and on the temperature. We refer to the waves as "sound"" in our everyday gaseous (i.e. air) and liquid (i.e. water) environments, but this and its associated terms such as "supersonic" are commonly extended to the same phenomena in any other fluid media. If an object travels through the medium faster than its "speed of sound" or "supersonically" shockwaves are generated, familiar to us as sonic booms from aircraft, bullets, cracking whips etc, which can usually be seen either directly or with some optical manipulations. Such shockwaves are (so I understand) seen being generated by the "bullets" of gas in M42 and some other nebulae, so the term "supersonic" is applicable. One could argue that sound-related terminology should be restricted to Earth-atmosphere/hydrosphere pressure waves audible to humans, and apply more general terminology to other cases, but this seems pointlessly obscurantist. 87.81.230.195 (talk) 15:08, 4 March 2009 (UTC).


 * That would indeed make it sound like the age-old (in)famous question of whether a falling tree makes noise in a forest where there is nobody to hear it!
 * Anyway the point of my intervention here now is that while the "bullets" of gas may indeed have a supersonic speed in "local" terms (i.e. as compared to the speed of sound in that medium), we can also see the sentence simply as meaning that they go faster than the sound in human-familiar conditions, i.e. a speed around 1200 km/h. It is a simplistic explanation, but it is still a good illustration for Mr. Everybody.
 * CielProfond (talk) 04:30, 5 March 2009 (UTC)

Thanks for the explanation. I found corroboration at the Gemini Observatory site on this page: http://www.gemini.edu/node/226 (great image!). Might it be worth including a reference to that page in the article? —Preceding unsigned comment added by 77.107.162.102 (talk) 16:47, 5 March 2009 (UTC)

Age of Bullets
The article talks about the nebula being some 1270 lightyears away from us. Yet, the bullets section says that "They (the bullets) were probably formed one thousand years ago from an unknown violent event." If this were the case, we wouldn't see the bullets for another 200 or so years. I know it's relative, but techinically speaking, it should really take the 1270 light years into account, and thus "They were probably formed around 2000 years ago..." --86.162.179.186 (talk) 11:59, 23 March 2009 (UTC)


 * It's common use in astronomy to speak of the date of an event from the date it was seen on Earth, in the present case meaning that the formation of the bullets would have been visible (if possible) about a thousand years ago. You are correct, though, in saying that it really formed about 2000 years (or 2270) ago, but this usage is rare in astronomy. Now, don't ask me the why of that! ;-) CielProfond (talk) 23:29, 23 March 2009 (UTC)

Ground based views, and location inside the constellation of Orion
It would be good if we get at least one ground-based view of the nebula, and one picture of the location of the nebula inside the constellation. Mighty useful for us amateur stargazers.  Lynch 7  14:51, 6 February 2012 (UTC)
 * Added image as part of cleanup. Fountains of Bryn Mawr (talk) 16:16, 6 February 2012 (UTC)
 * Thanks!  Lynch 7  16:55, 6 February 2012 (UTC)

The naked-eye image of Orion helps but the caption information "lower middle" is, well, nebulous. Only if you already know where it is, you can see it in this photo - but it would be much better to add an arrow pointing to the right location. Paulhummerman (talk) 01:55, 5 February 2021 (UTC)

Image sizes
I believe the 10,000 x 10,000 pixels & 18,000 × 18,000 pixels images are broken. — Preceding unsigned comment added by 99.54.188.176 (talk) 14:22, 4 March 2012 (UTC)

How impossible in the lab?
A colleague produced the new sentence
 * This radiation was quite impossible to reproduce in the laboratory because it depended on the quiescent and nearly collision-free environment found in deep space.

and justified it with
 * "all but impossible" means it was ALL things, except "impossible". Changed it to something less incorrect.

Actually, that's more seriously incorrect: "quite" means to a great extent, but something is either possible or not, and "quite impossible" is similar to "highly unique"; both are examples of a rhetorical device -- i'd call it "absurd hyperbole" -- that is unsuitable for an encyclopedia. Now, i hesitate to endorse "all but impossible". (...partly bcz i've got an eerie sense of having at least come close to making some kind of very similar objection on WP in the last year ... maybe even re this line!) But that replacement is the less correct of the two terms, since "all but ..." can mean "every item [of the kind implicitly specified] except ..."; at worst "all but X" is, in this case, something of a metaphor (applied to the continuum between "inevitable" and "impossible") for "too close to impossible for specifying the difference to be worth the effort it would take". Or "inexpressibly close to impossible". For the moment, i'm reverting. I think the sentence is crap for other reasons, and i think it's more to the point to work out a solution to the other shortcomings (which probably involve more of the 'graph), than the terminological vagueness the colleague was trying to remedy. And the solution for the problematic sentence may, when the graph is shaped up, fall out when shaken gently. --Jerzy•t 05:22, 29 September 2012 (UTC)

"Discovered by xxx" - what nonsense
It is visible to the naked eye. It was 'discovered' by early humans. — Preceding unsigned comment added by 82.68.94.86 (talk) 11:59, 16 May 2014 (UTC)
 * As the article says, it is visible and was known, but the nebulous nature of the object was discovered with telescopes. StarryGrandma (talk) 17:56, 16 May 2014 (UTC)
 * Was it visible to early humans though? It's interesting how it wasn't recorded until the 17th Century, when the Andromeda Galaxy, Messier 7 and Double Cluster were all noted centuries earlier. Even in the 18th Century there's the question of why M43 was listed as a separate object, when it's part of the same nebula. Did the nebula appear in two parts for a time before it reached its current visible size? Walshie79 (talk) 08:12, 14 December 2016 (UTC)

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 * APEX view of star formation and cosmic clouds in the Orion Nebula.jpg

Every Image Different
It's rather disconcerting that every image in the article is completely different, though they all show the same thing. It might be helpful to the baffled naive reader (what does it really look like?) to point out that each image differs in field of view, orientation, wavelength etc. Paulhummerman (talk) 01:48, 5 February 2021 (UTC)

Maybe all that’s needed is to rotate the images so that they overlay better? JdelaF (talk) 06:48, 27 March 2022 (UTC)

Messier's drawing from 1774 and memoir from 1771?
How can the Messier's drawing be a part from his memoir from 1771 when the date of the drawing is 24th March 1774 ("24 Mars 1774" is written in French on the upper right corne of the drawing). Agerskov (talk) 23:52, 31 January 2022 (UTC)

M42 v M43.
I added info re M43 to this pg. I somewhat regret this as overly “bold” on my part, but maybe this will provoke someone more knowledgeable to clarify what imho seems somewhat confusing. JdelaF (talk) 06:55, 27 March 2022 (UTC)

Formation theories
I seem to recall in my youth (Sixties) that there were opinions that this was the result of a supernova. Is that correct? If so, then these disproven theories should get a small mention. 50.111.39.61 (talk) 00:42, 15 June 2022 (UTC)


 * Well, that would hardly be surprising. See SSPSF model. However, I am not aware of any evidence that applies specifically to M42/43. Jmacwiki (talk) 03:58, 20 June 2022 (UTC)
 * Actually, I am, somewhat, maybe: Barnard's Loop is likely a very old (2 MYr) supernova remnant. This would have about the right age for the SN to have “caused” some of the newest stars in Orion. The whole nebula is much older than that, however. Also, there is no definitive link between the Loop and most of the new stars. Jmacwiki (talk) 04:33, 20 June 2022 (UTC)