M42--a mystery?

[kalasinman]

Just offering this for consideration. I read recently that Galileo did extensive observing of Orion, but failed to take note of M42, a naked eye object in our time. His notes from 1610 apparently omit it but later observers in mid century mention some nebulosity. Could this be? Could M42 have developed as we see it fairly recently?

[Alien 13]

Maybe the light polution was very bad in his day.

Alan

[romi]

... It is true that Galileo did not mention the Orion Nebula but there are some records that do, still in his days (between 1610-1620).

[Steve Ward]

From what I've just read he saw the nebulosity and noted that " the Sword of Orion would , with more powerful telescopes , be resolved into groups of small stars wonderfully arranged ".

[michael.h.f.wilkinson]

I assume the glare in his rather poor optics, combined with the very small aperture may have conspired against seeing the nebula.

[Owmuchonomy]

He also suffered cataracts and premature blindness to some extent, some historians putting it down to his constant (probably unprotected) solar observation.

[kalasinman]

From what I've just read he saw the nebulosity and noted that " the Sword of Orion would , with more powerful telescopes , be resolved into groups of small stars wonderfully arranged ".

So he saw the Trap, but what did he say about nebulosity? Just to be clear, with much more dim objects being noted by many naked eye observers over thousands of years, is there any report of the object we see so clearly today? I just think it's an interesting line of inquiry.

[kalasinman]

I assume the glare in his rather poor optics, combined with the very small aperture may have conspired against seeing the nebula.

Perhaps, but his optics were the best of the day. Again, this is a naked eye object in our time. I'm just curious as to whether what we see so clearly may be to an extent a recent development.

[michael.h.f.wilkinson]

I have actually seen the scope. It has about one inch of aperture. I have small 6x30 binoculars with dubious coatings (probably still better than no coatings). It is quite hard to make out the nebulosity with these bins. It is quite likely that the fumes over a city like Pisa would further aggravate problems given the fairly low altitude of M42. Galileo used 8, 20 and 30 times. Given the tiny aperture, the 8x would stand the best chance of seeing it.

I myself have a nineteenth-century brass spyglass with an achromatic objective of about 2" (much more advanced design than Galileo's, and certainly better optics) with Huygens type EP, and erecting lens. I have tried looking at the Orion nebula, and it is next to impossible. The moon does show good detail, and I can make out Jupiter's disk and moons. For nebulae, these scopes are not so good.

As for M42 being recent: In astronomical terms it is, as any OB star association, but the age is estimated as 3 million years. It is possible that new star formation has brightened the nebula, of course, but I do not think it very likely. A contemporary of Galileo did spot it in the same year Galileo observed the stars within it. Most scopes of the day used 3x magnification, giving significantly wider FOV and better surface brightness of the image. Both factors make it much easier to see the nebula than Galileo's design.

[Steve Ward]

Good representation of his FOV half way down the page here ...  http://scitechantiques.com/Galileo-Telescope-Anomalies-optics/

[Zakalwe]

Perhaps, but his optics were the best of the day.

Isn't that a bit like saying that because the Wright Bros didn't break the sound barrier then it couldn't be done? After all, they had the best plane of the day?

[kalasinman]

Points taken ,( or is it given? ) regarding G's kit. My own curiosity was aroused as this is one popular target, I myself am awed by what Messier accomplished, and with the millennia of dark skies and sharp eyed observers never quite got there. The Arabs? India? Ahh well, interesting to conjecture, at least on my side with my failing 20/300+ vision.

[kalasinman]

Isn't that a bit like saying that because the Wright Bros didn't break the sound barrier then it couldn't be done? After all, they had the best plane of the day?

No, not at all, as folks claim they actually see the nebulosity naked eye. The sound barrier? Hmmm, a stretch.

[michael.h.f.wilkinson]

Some sharp eyed people can see that the centre star of the sword is a bit fuzzy (especially under very dark skies). I have managed it, it was easiest from Queen Elizabeth National Park in Uganda, where there was little light and Orion was overhead .

[ronin]

Galileo likely didn't care what M42 was, it was likely just a bit of a fuzzy patch, made fuzzier by the bit of tube and glass he was pointing at it, whereas planets had a lot more going for them as far as he was concerned.

We do tend to look back 400 years but assume that they had something reasonably compariable to our present day equipment - They actually couldn't make a half decent lens, it took another 100 years for some lunatic to come up with the idea of a mirror. Our intrinsic knowledge of a telescope is way beyond Galileo's. We know how it works, how to arrange things, what bits to go get and the theory behind it.

These Galileo scopes are not, they are a tube of the appropriate shape with a modern machine ground precision lens is them at both ends.

[acey]

M42 is not a naked-eye object. The fuzziness in the sword that is easily visible at a dark site is due to the involved stars. There are many fuzzy groups of close stars in the sky, which were classed as nebulae by early astronomers. The head of Orion was considered a nebula, and I believe Galileo looked at that. He also studied the Beehive. The sky is very big, with lots of stuff to look at, and Galileo didn't have a guide book to help him. So really not surprising if he didn't pay much attention to Orion's sword. We take interest in it because we know what's there.