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Note: the dramatic photo is a composite, of Jupiter in visible light and its auroras captured in UV.

by Isamu 10y ago

jessriedel 10y ago
Thank you. It's criminal that that's not mentioned in the caption to the photograph. As a positive note, the composite videos they released are pretty wild: http://hubblesite.org/newscenter/archive/releases/2016/24/video/ http://hubblesite.org/newscenter/archive/releases/2016/24/vi...
- throwaway_xx9 10y ago
  > It's criminal that that's not mentioned in the caption to the photograph Well ... all satellite images are taken with sensors tuned for a specific frequency range, so essentially B+W, then false-colored for human display. Unless an astronaut with a Hasselblad is pointing the lens out to space, you won't get the normal exposure that you're thinking of.
- edgarvaldes 10y ago
  That detail is only exposed when you click in the image on the right. http://www.spacetelescope.org/images/heic1613a/ http://www.spacetelescope.org/images/heic1613a/
readams 10y ago
Nearly every photo of space you see, especially from Hubble, is usually a composite, falsely colored, or otherwise altered in ways that bring out the important features of the photo. Note that the idea of "true color" for these sorts of astronomical photos is itself a bit ill-defined. Here's some information about the kinds of manipulations that might go into these photos: http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/ http://hubblesite.org/gallery/behind_the_pictures/meaning_of...
- Kenji 10y ago
  >Note that the idea of "true color" for these sorts of astronomical photos is itself a bit ill-defined. Why? Because of Relativistic Doppler Effect?
  - dakr 10y ago
    Astronomical cameras don't capture color information in the sense that our eyes or consumer digital cameras do. They are "black and white" only detectors. To get color information, several images are taken with different filters in front of the detector. Afterwards, those images can be stacked and each layer assigned a color to create a composite image. Making this a "true color" image that exactly mimics what your naked eye would see ranges from difficult to impossible (like in the case of UV data). It's also unimportant, because we mostly use color images as a visual aide (of course!). The "science" is in comparing and contrasting the individual "color" images.
    - gus_massa 10y ago
      In some sense, digital cameras do the same. They have a different channel for red, green and blue, that are composited to provide something similar to true color. (Even old film cameras do something similar.) Sometimes you can get surprises. Most cameras can see some of the UV and infrared light.
    - steve19 10y ago
      This is exactly how CMOS/CCD image sensors (used in digital cameras) work [0]. Each "sub-pixel" is just a photocell which detects light intensity. A bayers filter on top of the sensor array filters light colors so different "sub-pixels" detect colors (light intensity of different parts of the visual spectrum) [1] Enthusiasts sometimes remove the filter to get higher optical resolution or better contrast B&W images. You can even buy consumer cameras with this feature off the shelf [2] NASA is doing the equivalent of instagram filters, making photos appear more appealing to the general public. NASA says (via. Space.com [3]): "Creating color images out of the original black-and-white exposures is equal parts art and science," NASA said. For example, Hubble photographed the Cat's Eye Nebula through three narrow wavelengths of red light that correspond to radiation from hydrogen atoms, oxygen atoms, and nitrogen ions (nitrogen atoms with one electron removed). In that case, they assigned red, blue and green colors to the filters and combined them to highlight the subtle differences. In real life, those wavelengths of light would be hard to distinguish for humans." In other words, ignore the colors. [0] https://en.wikipedia.org/wiki/Image_sensor https://en.wikipedia.org/wiki/Image_sensor [1] https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter [2] https://en.wikipedia.org/wiki/Leica_M_Monochrom https://en.wikipedia.org/wiki/Leica_M_Monochrom [3] http://www.space.com/8059-truth-photos-hubble-space-telescope-sees.html http://www.space.com/8059-truth-photos-hubble-space-telescop...
sandworm101 10y ago
And it isn't a very good one at that. The aurora overlay seems to be on a different rotational axis, as if the Jupiter image was taken while the planet was at a very different angle. It makes me wonder whether I can trust the height of these things, which in the image extend well above Jupiter's visible atmosphere. Is that reality, or a poorly-aligned overlay.

Note: the dramatic photo is a composite, of Jupiter in visible light and its auroras captured in UV.

by Isamu 10y ago

Note: the dramatic photo is a composite, of Jupiter in visible light and its auroras captured in UV.

Thank you. It's criminal that that's not mentioned in the caption to the photograph. As a positive note, the composite videos they released are pretty wild: http://hubblesite.org/newscenter/archive/releases/2016/24/video/ http://hubblesite.org/newscenter/archive/releases/2016/24/vi...

throwaway_xx9 10y ago
> It's criminal that that's not mentioned in the caption to the photograph Well ... all satellite images are taken with sensors tuned for a specific frequency range, so essentially B+W, then false-colored for human display. Unless an astronaut with a Hasselblad is pointing the lens out to space, you won't get the normal exposure that you're thinking of.
edgarvaldes 10y ago
That detail is only exposed when you click in the image on the right. http://www.spacetelescope.org/images/heic1613a/ http://www.spacetelescope.org/images/heic1613a/

readams 10y ago

Nearly every photo of space you see, especially from Hubble, is usually a composite, falsely colored, or otherwise altered in ways that bring out the important features of the photo. Note that the idea of "true color" for these sorts of astronomical photos is itself a bit ill-defined. Here's some information about the kinds of manipulations that might go into these photos: http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/ http://hubblesite.org/gallery/behind_the_pictures/meaning_of...

Kenji 10y ago
>Note that the idea of "true color" for these sorts of astronomical photos is itself a bit ill-defined. Why? Because of Relativistic Doppler Effect?
- dakr 10y ago
  Astronomical cameras don't capture color information in the sense that our eyes or consumer digital cameras do. They are "black and white" only detectors. To get color information, several images are taken with different filters in front of the detector. Afterwards, those images can be stacked and each layer assigned a color to create a composite image. Making this a "true color" image that exactly mimics what your naked eye would see ranges from difficult to impossible (like in the case of UV data). It's also unimportant, because we mostly use color images as a visual aide (of course!). The "science" is in comparing and contrasting the individual "color" images.
  - gus_massa 10y ago
    In some sense, digital cameras do the same. They have a different channel for red, green and blue, that are composited to provide something similar to true color. (Even old film cameras do something similar.) Sometimes you can get surprises. Most cameras can see some of the UV and infrared light.
  - steve19 10y ago
    This is exactly how CMOS/CCD image sensors (used in digital cameras) work [0]. Each "sub-pixel" is just a photocell which detects light intensity. A bayers filter on top of the sensor array filters light colors so different "sub-pixels" detect colors (light intensity of different parts of the visual spectrum) [1] Enthusiasts sometimes remove the filter to get higher optical resolution or better contrast B&W images. You can even buy consumer cameras with this feature off the shelf [2] NASA is doing the equivalent of instagram filters, making photos appear more appealing to the general public. NASA says (via. Space.com [3]): "Creating color images out of the original black-and-white exposures is equal parts art and science," NASA said. For example, Hubble photographed the Cat's Eye Nebula through three narrow wavelengths of red light that correspond to radiation from hydrogen atoms, oxygen atoms, and nitrogen ions (nitrogen atoms with one electron removed). In that case, they assigned red, blue and green colors to the filters and combined them to highlight the subtle differences. In real life, those wavelengths of light would be hard to distinguish for humans." In other words, ignore the colors. [0] https://en.wikipedia.org/wiki/Image_sensor https://en.wikipedia.org/wiki/Image_sensor [1] https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter [2] https://en.wikipedia.org/wiki/Leica_M_Monochrom https://en.wikipedia.org/wiki/Leica_M_Monochrom [3] http://www.space.com/8059-truth-photos-hubble-space-telescope-sees.html http://www.space.com/8059-truth-photos-hubble-space-telescop...

sandworm101 10y ago

And it isn't a very good one at that. The aurora overlay seems to be on a different rotational axis, as if the Jupiter image was taken while the planet was at a very different angle. It makes me wonder whether I can trust the height of these things, which in the image extend well above Jupiter's visible atmosphere. Is that reality, or a poorly-aligned overlay.