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Earl

Would we see nebuloisty if it was local?

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Looking at a deep image of M42 with all the assosciated nebulosity, if you were there rather than here would it be visable? would you be in cloudy space like murky water? or is the scale so large it might not be locally visable?

Edited by Earl
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humm, it sort of answers the question, I wonder what our area of spaces look like from 500 lightyears away.

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Anyone who's flown in an aeroplane has some experience of this. When you fly through cloud do you see clouds? I would say, not really. You see cloud, which isn't the same thing. To paraphrase a well known saying, you can't see the clouds for the cloud.

Nebulae are clouds. The closer you get to them the more diffuse they become - or so I would assume since, obviously, I haven't done it!  There might be an optimum distance for seeing M42 and I suspect that we are quite some distance from that optimal point - but get too close and it will visually evaporate, so to speak.

You'll often read that M42 is less dense than the best laboratory vacuums created on Earth. One of our guests, a researcher at Manchester Uni, picked me up on this. She said that they now have a vacuum less dense than M42 but still that gives you an idea that M42, seen from within, might seem like much ado about nothing!  :grin:

Olly

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Thank you posting the entertaining video which described how cameras can depict the beauty of the cosmos including nebula so much better than what it calls 'meat cameras' (eyes). I enjoyed it. A picture taken on a starry night might show the dark outline of the surroundings from background light if you are lucky, but a black, feature less sky. The same results when cameras picture the heavens on the Moon. In fact I don't think I have ever seen a successful picture of the heavens from any craft on the Moon or Mars. Bottom line, I find it difficult to grasp why cameras are so good at capturing deep space beauty, but so ineffective at capturing the heavens. 

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+1 for this scenario, if you compress several light years worth of almost nothing into the small apparent space which we see from here it must look brighter than it does close up.  :smiley:

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 I find it difficult to grasp why cameras are so good at capturing deep space beauty, but so ineffective at capturing the heavens. 

I genuinely don't follow. What is the difference between 'deep space' and 'the heavens?' I'm not flying a kite, it's an honest question.

Olly

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Thank you posting the entertaining video which described how cameras can depict the beauty of the cosmos including nebula so much better than what it calls 'meat cameras' (eyes). I enjoyed it. A picture taken on a starry night might show the dark outline of the surroundings from background light if you are lucky, but a black, feature less sky. The same results when cameras picture the heavens on the Moon. In fact I don't think I have ever seen a successful picture of the heavens from any craft on the Moon or Mars. Bottom line, I find it difficult to grasp why cameras are so good at capturing deep space beauty, but so ineffective at capturing the heavens. 

Umm....O kaaaaayyy....

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I don't think I have ever seen a successful picture of the heavens from any craft on the Moon or Mars...

I guess one of the reasons you don't find deep space images taken from the Moon or Mars is because the exercise would be redundent. Hubble is putting on an excellent show while vehicles on the Moon or Mars are getting on with their own investigations. Indeed, it would be a little odd to plan a journey to Mars, for example, and after all that expense and mind-blowing expertise have your land based laboratory ignore the surface and start taking snap shots of distant galaxies. 

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In fact I don't think I have ever seen a successful picture of the heavens from any craft on the Moon or Mars.

Maybe you haven't looked? There were UV images taken from Apollo 16

http://www.lpi.usra.edu/lunar/missions/apollo/apollo_16/experiments/f_ultra/

http://en.wikipedia.org/wiki/Far_Ultraviolet_Camera/Spectrograph

Typically though, there was no reasons to take photos of the sky from the Moon...after all, the astronauts were there to study the Moon.

You would also need to understand that you would still need long exposures, and thus a tracking mount. All that increases complexity and weight, for very little (if any) gain. Plus the cameras that were sent to the Moon (on Apollo) were designed to take photographs during the Lunar daytime, not nighttime.

Similarly with the Mars missions, every ounce counts. What could possibly be gained from sending a small telescope and camera to Mars to take poorer images than could be taken from the Earth?

Edited by Zakalwe

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Maybe we are part of the Grand Design, and deliberately stuck on our little rock for the purpose 

of seeing all the beauty, and colourful  content of the universe. Albeit via the camera sensor/film.

If our eyes were huge enough, perhaps we could ditch the scopes lenses and cameras.

Perhaps we should be grateful that we see what we see from our little world. 

Maybe we need to earn  a ringside seat, although as the Video explains, it wouldn't help one bit   :rolleyes::smiley:.

Ron.

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I genuinely don't follow. What is the difference between 'deep space' and 'the heavens?' I'm not flying a kite, it's an honest question.

Olly

Every person seems not to have followed what I was trying to convey. If you look up to the sky on a starry night you see the splender of the milky way, the constellations and on average, a shooting star every 10 minutes. Point any household  camera to the same sky - click - and the result is a black, feature less image. For a camera to see the starry sky you need to nurse maid it with a tracking mount and long exposure time. Even high definition  digital cameras are ineffective at capturing the stars above without troublesome help, yet our eyes capture the splender with ease. I am bewildered how people are in awe of camera prowess, when cameras can't even easily capture what we take for granted.         

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Every person seems not to have followed what I was trying to convey. If you look up to the sky on a starry night you see the splender of the milky way, the constellations and on average, a shooting star every 10 minutes. Point any household  camera to the same sky - click - and the result is a black, feature less image. For a camera to see the starry sky you need to nurse maid it with a tracking mount and long exposure time. Even high definition  digital cameras are ineffective at capturing the stars above without troublesome help, yet our eyes capture the splender with ease. I am bewildered how people are in awe of camera prowess, when cameras can't even easily capture what we take for granted.         

Ahh, I see.

A camera will easily capture the stars with a few seconds exposure. It's our crummy wetware eyes that is the limitation. We have no colour vision in dim light, our visual system can only integrate a few seconds of vision, our vision system is easily fooled by the simplest of optical illusions and we can only see in a very narrow part of the full spectrum.

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The most common colour in the Galaxy is deep red from all the hydrogen, pity out dark adapted eyes are so rubbish at picking it up as there are lots of nice big nebulae up there that are cool to see. You need to give the "meat cameras" a bit of a help to allow them to see things more clearly... Good fun to see barnards loop wrapped round orion and the North america just hanging there.

Cheers

Peterw

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A nifty fifty lens is pretty quick at star grabbing. Give 30 seconds and you'll be surprised at what it collects, and probably not much trailing.

Especially areas of sky at the higher declinations.

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Yet, all the sophistication and prowess of the best lenses and cameras in the universe is absolutely, completely and utterly useless without the subsequent observation from our "wetware" and crummy little eyes :)

Edited by Joves

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Think this sums up our crummy little things called eyes best:

"OUR EYESIGHT

Eyesight is an engineering marvel. Think about it. Our eyes have an automatic iris. automatic focus. an aspheric lens, a curved image surface, a chemical image intensifier, a windshield washer-wiper, and a lens cover, all as standard equipment. And this is without mentioning the wonder of stereo vision!"

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Think this sums up our crummy little things called eyes best:

"OUR EYESIGHT

Eyesight is an engineering marvel. Think about it. Our eyes have an automatic iris. automatic focus. an aspheric lens, a curved image surface, a chemical image intensifier, a windshield washer-wiper, and a lens cover, all as standard equipment. And this is without mentioning the wonder of stereo vision!"

We also have our retinas "back to front, with the blood vessels lying on top of the photosensitive cells which blocks the incoming light. The octopus, on the other hand, has the blood vessels behind the retina which makes their eyes more sensitive.  Similarly, the photosensitive receptors face away from the incoming light, and the nerves exit in the path of the incoming light. The nerves then trail across the eyeball's inside surface to exit the retina at the correctly-named 'blind spot'. 

The image processing centre of the brain is at the rear of the head, which means that the signals from the eyes have to travel to furthest distance. This slows our responses.

Our night vision is reduced as we don't have a  tapetum lucidum. Our night vision is also affected by moving from light to dark. The rhodopsin that is broken down by light photons has to be recombined in the liver and transit back to the eye cells.

:grin:

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Cool video, btw, Zakalwe. Kinda makes me feel like we have the prime seat for viewing all the stuff we view, thinking for some reason we are soooo far away from it!

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We also have our retinas "back to front, with the blood vessels lying on top of the photosensitive cells which blocks the incoming light. The octopus, on the other hand, has the blood vessels behind the retina which makes their eyes more sensitive.  Similarly, the photosensitive receptors face away from the incoming light, and the nerves exit in the path of the incoming light. The nerves then trail across the eyeball's inside surface to exit the retina at the correctly-named 'blind spot'. 

The image processing centre of the brain is at the rear of the head, which means that the signals from the eyes have to travel to furthest distance. This slows our responses.

Our night vision is reduced as we don't have a  tapetum lucidum. Our night vision is also affected by moving from light to dark. The rhodopsin that is broken down by light photons has to be recombined in the liver and transit back to the eye cells.

:grin:

Quote that exact post to a blind person and realise how ungrateful and blasé we can be :)

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:D Yes, in fairness to "eyes", their real time sensitivity has not been 

greatly bettered by the most sensitive (large pixel) video cameras. 

It's about the SAME according to my understanding. :p

One of the more intriguing things (to me) is that, in tandem with the

brain, the image is seamlessly "blanked" when we turn our head.

We don't get dizzy. We have inbuilt "auto-guiding"?   ;)

Edited by Macavity
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Not to mention depth of field. Dare I say, there will never be a camera lens designed that can match that of the human eye. And, even if there is, how are we ever to know?! :p

Edited by Joves

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Quote that exact post to a blind person and realise how ungrateful and blasé we can be :)

Well, I'm not ungrateful (who would I be grateful to?) and certainly not blase. :grin:

It was just to show that, remarkable as the human vision system is, it is far from perfect.

As an aside, I can recommend this book, which illustrates the complexity of the brain and senses, especially when things go wrong.

http://www.amazon.co.uk/Tale-Duelling-Neurosurgeons-Revealed-Recovery/dp/0857522191/ref=sr_1_1?ie=UTF8&qid=1422875057&sr=8-1&keywords=duelling+neurosurgeons

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Well, I'm not ungrateful (who would I be grateful to?) and certainly not blase. :grin:

It was just to show that, remarkable as the human vision system is, it is far from perfect.

As an aside, I can recommend this book, which illustrates the complexity of the brain and senses, especially when things go wrong.

http://www.amazon.co.uk/Tale-Duelling-Neurosurgeons-Revealed-Recovery/dp/0857522191/ref=sr_1_1?ie=UTF8&qid=1422875057&sr=8-1&keywords=duelling+neurosurgeons

Haha, I know, mate. I'm pretty sure none of us on this forum are unappreciative of our eyesight. It'd be a pretty bland hobby without it. Was just sticking up for the little guy (little guy = eyes on this occasion)! ;)

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