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Thread: The Many Faces of Venus

  1. #1
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    The Many Faces of Venus

    As your heliochromologist (wink) it should be obvious that the "true" colors of the planets are due to the Sun's light. Thus the many wonderful and bizarre color portrayals of our nearest neighboring planet, Venus, should interest us and I'm one who's justified in presenting it. [Pause for beating chest and eating yellow Sun-ripe banana.]

    A few years ago I searched fairly hard to find a "natural color" rendering for Venus. Given its brightness and proximity, I was a bit surprised. I found some serious work by Richard Nunes (?) that seemed reasonable, certainly far better than the traditional red radar renditions. His work, and others perhaps since his work, seem to use the Mariner 10 images, but these seem to be taken from an orange and a UV filter, thus limited in not only a true-color result but the greater emphasis from UV of clouds would be difficult, I think, to take into account.

    Many sites because they are science-based state that the images use false coloring. But you might be surprised how many of them don't bother.

    The Messenger image, however, uses red, green, and blue filters, apparently, and would seem to be ideal for something close to a true color rendering. I found it at the Planetary Society.

    Planetary Soc RGB image.jpg

    For fun and to see just how often the color variations for Venus are on the internet, I entered "planet Venus" into the Google machine to see what came out. I was curious how many sites I would find before getting to one that had it "right". I gave up after 75. You might enjoy what has been represented for the "planet Venus". I entered the goddess(?) -- on page 2 -- because her color is far more accurate than most.

    Venus colors 1 of 3.jpg

    To see the images of each site, simply do the Google search for "planet Venus". They are done in order and shown using the three-column format.

    [two more to follow]
    Last edited by George; 2018-Jul-12 at 08:19 PM.
    We know time flies, we just can't see its wings.

  2. #2
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    Next page.

    Venus colors 2 of 3.jpg


    BTW, if I were to grade them on any of their choice for the Sun's color, guess what it would be?

    Perhaps 10 years or so from now, we can come back here and note how much more accurate the sites become for both the Sun, which has been improving, and for Venus. The other planets are sitting nicely, I think.
    Last edited by George; 2018-Jul-13 at 02:44 PM.
    We know time flies, we just can't see its wings.

  3. #3
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    Last edited by George; 2018-Jul-13 at 07:26 PM.
    We know time flies, we just can't see its wings.

  4. #4
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    Quote Originally Posted by George View Post
    Last page...

    Attachment 23451
    Your attachments are giving me "invalid attachment" messages.

    As a reflector, we can define true color by means of the difference between the incident and reflected light. My old Norton's Star Atlas gives its color index as about 1.2, similar to a K star. If attenuated for comfort it should look very pale yellowish white or pale beige if the Sun is dominating our ambient light.

  5. #5
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    Quote Originally Posted by Hornblower View Post
    Your attachments are giving me "invalid attachment" messages.
    This is my second attempt to fix it. I assume that the file sizes are a bit large (~750k), which is kinda necessary to show so many different images. When I first post them, they are fine but something happens and they won't work.

    It seems that only page 3 needed correction, which I have edited. Are they working now?

    As a reflector, we can define true color by means of the difference between the incident and reflected light. My old Norton's Star Atlas gives its color index as about 1.2, similar to a K star. If attenuated for comfort it should look very pale yellowish white or pale beige if the Sun is dominating our ambient light.
    Why are you thinking like an astronomer? Oh yeah, ok.

    Since color is strictly an eye/brain perception, my preference for a "true color" or "natural color" definition would be what an object simply looks like to the human eye as we would normally see it. This would be for the up close and personal (extended) views of these objects. That's what we see every day, but that's after atmospheric extinctions of sunlight, admittedly. I don't know that we have ever tackled it, but the reduction in the blue-end of the spectrum by our atmosphere could potentially cause objects that we would see from a spaceship might look a little more blue than with a quality reflector from Earth. My guess is that it would not make any difference more often than not. The photon flux distribution, as we have talked about in the past, is remarkably flat for an AM0 sp. irr. and I suspect the eye might see this as an almost perfect white standard. [That's speculation on my part, of course.] Also, color constancy is quite powerful and the eye is quick to recalibrate in order to render true color unless the incident light spectrum is highly altered.

    Another way to put it would be what an object (eg planet) looks like if we go there and take quality pictures of it, or if we go there and shrink it then bring it back with us and put it in the Smithsonian, but with quality lighting upon it of course. I doubt we would see much difference.

    For Venus, the subtle difference we see between the Mariner "natural color" attempt and the Messenger attempt are notable but trivial when we consider all the bizarre colors chosen for it as I demonstrate, most of which don't bother to mention that they are false color images. They seem content to regurgitate that red radar image year after year. But, I don't want to be overly critical since we all need a little artistic touch now and then, especially for a vanilla white Sun. [Don't tell anyone I said that, of course..]
    Last edited by George; 2018-Jul-13 at 07:52 PM.
    We know time flies, we just can't see its wings.

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