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Thread: Imaging the Suns photosphere

  1. #1
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    Imaging the Suns photosphere

    If the photosphere of the Sun is the region producing visible light, then why is it
    so difficult to obtain an image of this light from space? There are no images that I
    can find that have been taken by anything resembling a normal camera, with a solar
    filter.

    This is an image of the photosphere, from the SDO, but the 'camera' is a little more
    complex than I would have thought necessary.

    Perhaps someone can explain to me why a Michelson Interferometer is the device
    required to 'see' visible light, from space?

  2. #2
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    The HMI is certainly a very complex camera but it's purpose is not simply to take pictures of the photosphere. Quote from HMI home page " HMI provides four main types of data: dopplergrams (maps of solar surface velocity), continuum filtergrams (broad-wavelength photographs of the solar photosphere), and both line-of-sight and vector magnetograms (maps of the photospheric magnetic field).

    You can snap a picture of the photosphere with any old camera WITH A SOLAR FILTER IF YOU DON'T WANT TO FRY THE CAMERA.

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    The major reason you don't send a simple camera into space is that are spending millions on a satellite and launcher - so the relative cost of sending up a complex (and way, way more useful) camera is negligible compared to the cost of the rest of the system. You wouldn't spend $50M to send a $100 system into space. You'd spend a million and send something that is really worth sending into space! And if you are only able to afford a simple camera then the odds are that even if you piggy back on another mission (like some universities get to) you can't afford all the pointing and aiming system integration.

  4. #4
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    You can snap a picture of the photosphere with any old camera WITH A SOLAR FILTER IF YOU DON'T WANT TO FRY THE CAMERA.
    From Earth maybe, but then why are there no similar images from any of the ISS EVA
    members? I suppose I should just pose a simple, straightforward question here, as
    this is Q&A.
    "Using a normal film or digital camera equiped with a Solar filter, can an image of the
    Sun be acquired from space which looks like an image of the Sun taken with the same
    camera and filter from Earth?"

    And I wonder if the camera was fried when this shot was taken? No atmosphere to provide any protection from the harsher wavelengths.
    http://chamorrobible.org/images/phot...996-medium.jpg

  5. #5
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    Quote Originally Posted by Solon View Post
    If the photosphere of the Sun is the region producing visible light, then why is it
    so difficult to obtain an image of this light from space? There are no images that I
    can find that have been taken by anything resembling a normal camera, with a solar
    filter.

    This is an image of the photosphere, from the SDO, but the 'camera' is a little more
    complex than I would have thought necessary.

    Perhaps someone can explain to me why a Michelson Interferometer is the device
    required to 'see' visible light, from space?
    Perhaps you can explain to me why you inferred that any special instruments were required to see visible light from space. My educated guess is that the researchers were using the spacecraft instruments to observe spectral components such as far ultraviolet and x-rays that are unobservable from the ground. Perhaps the relatively trivial exercise of taking a visible light photo like what we can easily take from the ground is a waste of precious spacecraft time.

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    "Using a normal film or digital camera equiped with a Solar filter, can an image of the
    Sun be acquired from space which looks like an image of the Sun taken with the same camera and filter from Earth?"
    In space you would also need good filters to ensure only light in the visible part of spectrum enters the camera. Much of the light outside the visible spectrum is filtered out by the atmosphere when you are on Earth.

    And I wonder if the camera was fried when this shot was taken? No atmosphere to provide any protection from the harsher wavelengths.
    http://chamorrobible.org/images/phot...996-medium.jpg
    No the camera was not fried - it took a good picture. The camera obviously has appropriate filters. It is just a matter of exposure time. The exposure was set to capture good detail of the Earth's surface and the spacecraft's arm, but this means the Sun is overexposed. They could have used a much shorter exposure but that would have resulted in a very uninteresting picture - all black with a little circle of the Sun's disk.

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    @Hornblower
    Perhaps you can explain to me why you inferred that any special instruments were required to see visible light from space.
    Simply because after following the manned spaceflight missions for over 40 years, I
    have not seen an image of a round disk sun, as we can see from the Earth, taken from space.
    Perhaps the relatively trivial exercise of taking a visible light photo like what we can easily take from the ground is a waste of precious spacecraft time.
    I wouldn't say it was a trivial exercise, surely any information we can acquire must
    add to our knowledge base. The few seconds it would take to install a filter and
    take a photo of the Sun is not going to wreak havoc on the financial or time constraints of the NASA missions?

    @TonyE
    In space you would also need good filters to ensure only light in the visible part of spectrum enters the camera. Much of the light outside the visible spectrum is filtered out by the atmosphere when you are on Earth.
    Fair enough. Would you have any idea of what type of filters would be required? I read that the latest version of the Star Tracker camera recently sent to the ISS for testing, and that will be used on the FASTSAT project, uses a transmission grating to pass only the visible wavelengths.
    http://www.nrl.navy.mil/media/news-releases/25-11r/
    http://www.scribd.com/doc/48749780/N...icro-Satellite
    No the camera was not fried - it took a good picture. The camera obviously has appropriate filters.
    I have not found any information on filters being fitted to this camera, I'd be interested to find out more, if you have references. For the lighting and colors of the image to look 'right', I wonder what kind of filter it would be?

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    Quote Originally Posted by Solon View Post
    Simply because after following the manned spaceflight missions for over 40 years, I
    have not seen an image of a round disk sun, as we can see from the Earth, taken from space.
    http://sohowww.nascom.nasa.gov/sunspots/
    http://www.spaceimages.com/sun.html
    http://sdo.gsfc.nasa.gov/gallery/main.php?v=item&id=67
    http://jsoc.stanford.edu/data/hmi/images/latest/
    http://sohowww.nascom.nasa.gov/galle...FDslow4_lo.mov

    I wouldn't say it was a trivial exercise, surely any information we can acquire must
    add to our knowledge base. The few seconds it would take to install a filter and
    take a photo of the Sun is not going to wreak havoc on the financial or time constraints of the NASA missions?
    I don't get it. We know what the sun looks like when photographed from Earth. If you were to take an equivalent (filtering out the stuff that doesn't get through the atmosphere) photo from space then it would obviously look the same. So why bother? On the other hand, as there are frequencies that can only be detected in space, then it makes sense to send up instruments to exploit that fact and learn things that we can't observe on earth. Am I missing the point of your question?

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    Those are all instrumentally detected, computer processed images. My question was about an ordinary camera, with off-the-shelf filters. The question was not about why we would bother, but if it is possible. You say it obviously is, given the correct filtering, so I have contacted some solar filter manufacturers to ask what the appropriate filters would be.

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    Quote Originally Posted by Solon View Post
    Those are all instrumentally detected, computer processed images. My question was about an ordinary camera, with off-the-shelf filters.
    And, of course, if you used a digital camera then that would be a "instrumentally detected, computer processed" image as well.

    but if it is possible. You say it obviously is, given the correct filtering
    Of course it is possible, why on earth (excuse the pun) wouldn't it be? It is obviously possible without any filter as well, although the exposure may well go wrong if the metering sensitivity doesn't match the image sensor (or film).

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    Quote Originally Posted by Solon View Post
    Those are all instrumentally detected, computer processed images. My question was about an ordinary camera, with off-the-shelf filters. The question was not about why we would bother, but if it is possible. You say it obviously is, given the correct filtering, so I have contacted some solar filter manufacturers to ask what the appropriate filters would be.
    A thick piece of so-called flint glass, which if I am not mistaken has a lot of lead in it, should filter out the far ultraviolet and x-rays nicely.

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    Thousand Oaks make suitable filters that they claim are used on the space shuttle.

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    @Strange
    And, of course, if you used a digital camera then that would be a "instrumentally detected, computer processed" image as well.
    Touche. The difference would be down to the optics in that case.
    Of course it is possible, why on earth (excuse the pun) wouldn't it be? It is obviously possible without any filter as well, although the exposure may well go wrong if the metering sensitivity doesn't match the image sensor (or film).
    I had a reply from one of the filter manufacturers, but...
    All our e-mails are meant exclusively for the recipient of the respective e-mail. We do not agree with unauthorized publication or quotation to persons other than the recipient of all or parts of this e-mail!
    I think I am permitted to say that he does agree with you, but that further IR/UV filtering might be required depending on the sensitivity curve of the camera. As to why there are no visible or white-light images from space, well, nobody is interested enough. I find that difficult to believe though, I mean Americans, after the Japanese perhaps, seem eager to photograph even the most mundane of subjects! No offence to either party intended.

    So, it looks like 'case closed' as far as expert opinion is concerned, though I'll keep trying to persuade someone in some space agency to snap the Sun for me, just to satisfy my obviously overactive sense of inquisitiveness.

    Thousand Oaks make suitable filters that they claim are used on the space shuttle.
    Thanks TonyE.

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    From the page linked in your other thread: http://www.lovethesepics.com/wp-cont...ng-the-Sun.jpg

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    Quote Originally Posted by Solon View Post
    @Strange

    Touche. The difference would be down to the optics in that case.

    I had a reply from one of the filter manufacturers, but...

    I think I am permitted to say that he does agree with you, but that further IR/UV filtering might be required depending on the sensitivity curve of the camera. As to why there are no visible or white-light images from space, well, nobody is interested enough. I find that difficult to believe though, I mean Americans, after the Japanese perhaps, seem eager to photograph even the most mundane of subjects! No offence to either party intended.

    So, it looks like 'case closed' as far as expert opinion is concerned, though I'll keep trying to persuade someone in some space agency to snap the Sun for me, just to satisfy my obviously overactive sense of inquisitiveness.



    Thanks TonyE.
    You are not understanding the answer you are being given. The cameras and lenses in question are identical to todays ground based cameras and filters. You are missing the fact that a modern digital camera is the same thing as that is found on todays most advanced telescopes and space based cameras.

    There is no functional difference between a space based camera and a ground based camera anymore.

  16. #16
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    " Imaging the Suns photosphere "
    It is a subject of great thought that which is the real image of Suns photosphere.
    Some time's I think is it the real Image of Sun which I know ?

  17. #17
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    Quote Originally Posted by Solon View Post
    You can snap a picture of the photosphere with any old camera WITH A SOLAR FILTER IF YOU DON'T WANT TO FRY THE CAMERA.
    And I wonder if the camera was fried when this shot was taken? No atmosphere to provide any protection from the harsher wavelengths.
    http://chamorrobible.org/images/phot...996-medium.jpg
    As others have said in different ways. This was not a picture of the photosphere, it was a picture of something else with the sun in it.
    But; that got me thinking.
    Not only would you need a filter, but you would need a telephoto lens as well if you want any resolution to the picture. I google searched some images of the sun, and I don't see anything worth seeing until the picture was shot with something more than 200mm.

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    This is the kind of shot I'm looking for from the ISS. Use the same camera and setup and let's see what it looks like. Of course they would need to take an ND filter, but I don't think they have one up there. They do have lenses up to 800mm though.
    200mm | ISO 50 | f/13 | 1/8000sec | 10 stop ND filter

    http://mcalisterium.wordpress.com/2011/09/30/sun-spots/

  19. #19
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    Quote Originally Posted by Solon View Post
    This is the kind of shot I'm looking for from the ISS. Use the same camera and setup and let's see what it looks like. Of course they would need to take an ND filter, but I don't think they have one up there. They do have lenses up to 800mm though.
    200mm | ISO 50 | f/13 | 1/8000sec | 10 stop ND filter

    http://mcalisterium.wordpress.com/2011/09/30/sun-spots/
    That would require a yellow filter.

    A 10 stop ND filter is a great idea and may be just enough attenuation to work. Astronaut Don Pettit is one of the more active ISS photographers and has had some great shots from the cupola. He is friends with a local astrophotographer and author who might be able to get such a filter to Don for his next flight... in 5 years. I'll make the suggestion, though maybe others here have contact with others going up sooner.

    This time last year aboard the ISS, Don had hoped to do a pin-hole solar projection but, for some reason, didn't get to do it. Shucks! A heliochromological set-back.

    [Added: I see that there is a 13 stop ND filter. This would be even better. What is the darkest and how neutral are they?]
    Last edited by George; 2013-Mar-22 at 03:11 AM.

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