4 ms·

Why can't you see any stars in these pictures or the video they posted? I'd expect to see thousands of stars.

by exhilaration 7y ago

hackerbabz 7y ago
The exposure is adjusted for Saturn which is much brighter than the stars.
- macintux 7y ago
  Same thing that people ask about the Moon landing photos. Where are the stars?
- exhilaration 7y ago
  Thank you, that makes perfect sense. I would still love to see what it looks like with the naked eye.
- jonbronson 7y ago
  That said, it would be amazing to see HDR images of these stellar bodies.
  - ksaj 7y ago
    Here's a picture of some of the light even HDR wouldn't likely uncover: https://www.esa.int/spaceinimages/Images/2007/07/The_constellation_Orion_and_the_winter_Milky_Way https://www.esa.int/spaceinimages/Images/2007/07/The_constel... EDIT: A larger version of the image, with an equally huge url: https://m.esa.int/var/esa/storage/images/esa_multimedia/images/2007/07/the_constellation_orion_and_the_winter_milky_way/9242622-5-eng-GB/The_constellation_Orion_and_the_winter_Milky_Way_article_mob.jpg https://m.esa.int/var/esa/storage/images/esa_multimedia/imag...
    - the8472 7y ago
      HDR and wide-spectrum are extensions along different measurement axes.
- tabtab 7y ago
  Similarly, fake-moon-landing conspiracists don't seem to understand the large magnitude of differences between heavily objects. Sunlight is typically so much brighter than stars such that the exposures best used in sunlight will wash out stars (make their images be swamped by sensor noise). This happens even as far out as Saturn, which gets much less sun than our moon. Thus the "no stars in photos" argument about Apollo holds no water. Even in a backyard telescope, if you look at Saturn, its brightness will wash out all but the very brightest of nearby stars because your eye adjusts for Saturn's brightness, not star brightness. (One nearby "star" you may see is actually the moon Titan.) The New Horizons probe did pick up star images in Ultima-Thule images, if you look at the raw exposures, but Ultima-Thule is really far away from the sun, beyond Pluto. And it's a dark body, requiring sensitive camera settings. Note that some raw exposures from some probes will show streaks that may be mistaken for stars, but are actually cosmic rays. They are usually digitally removed from final versions. The boundary where planetary exposures will start to clearly show stars is roughly around Neptune's or Pluto's orbit. But processing may have to remove them because time-lapse and/or multiple exposures may be needed to properly capture dim planets and rocky bodies that far out. Any stars caught would otherwise look smeared or smugdy.
avar 7y ago
Because they choose not to take photos of the surrounding stars, and those that are visible they either photoshop out or process the images in such a way that they're not visible. There's a sibling comment saying it's due to the exposure, that's wrong. That's not how Hubble works, it's not just a giant digital camera in orbit. The "photo" you're looking at is a composite from tens or hundreds of other images, so to start with most of the pixels you're looking at are just black filler. You can see the black and white raw images at http://hst.esac.esa.int/ehst/#home http://hst.esac.esa.int/ehst/#home search for "SATURN" under "Solar System Objects" and sort by date. A lot of the Hubble images from June 20th, 2019 have stars, including some visible between the rings and Saturn. They were just edited out because showing them wasn't the point.
- michelb 7y ago
  Is there a good explanation/article about how they take/process these images? I would have liked it if they could have included a bit of text about why certain items were not in the picture/removed.
- biot 7y ago
  Are those stars? The “iduy37thq” image [0], for example, has various star-like points of light on top of the planet itself in addition to appearing in the background. [0] http://hst.esac.esa.int/ehst-sl-server/servlet/data-action?RETRIEVAL_TYPE=PRODUCT&ARTIFACT_ID=iduy37thq_flt.jpg http://hst.esac.esa.int/ehst-sl-server/servlet/data-action?R...
  - Ididntdothis 7y ago
    This look like the noise I get from my camera when I take very long exposures (> 10 minutes). The sensor starts heating up and producing these dots.
  - xioxox 7y ago
    No they're probably not (I'm an astronomer). They're likely cosmic rays. When I've used Hubble data, then the processing uses multiple images to remove the cosmic rays (which aren't in common between images).

Why can't you see any stars in these pictures or the video they posted? I'd expect to see thousands of stars.

hackerbabz 7y ago

The exposure is adjusted for Saturn which is much brighter than the stars.

macintux 7y ago
Same thing that people ask about the Moon landing photos. Where are the stars?
exhilaration 7y ago
Thank you, that makes perfect sense. I would still love to see what it looks like with the naked eye.
jonbronson 7y ago
That said, it would be amazing to see HDR images of these stellar bodies.
- ksaj 7y ago
  Here's a picture of some of the light even HDR wouldn't likely uncover: https://www.esa.int/spaceinimages/Images/2007/07/The_constellation_Orion_and_the_winter_Milky_Way https://www.esa.int/spaceinimages/Images/2007/07/The_constel... EDIT: A larger version of the image, with an equally huge url: https://m.esa.int/var/esa/storage/images/esa_multimedia/images/2007/07/the_constellation_orion_and_the_winter_milky_way/9242622-5-eng-GB/The_constellation_Orion_and_the_winter_Milky_Way_article_mob.jpg https://m.esa.int/var/esa/storage/images/esa_multimedia/imag...
  - the8472 7y ago
    HDR and wide-spectrum are extensions along different measurement axes.
tabtab 7y ago
Similarly, fake-moon-landing conspiracists don't seem to understand the large magnitude of differences between heavily objects. Sunlight is typically so much brighter than stars such that the exposures best used in sunlight will wash out stars (make their images be swamped by sensor noise). This happens even as far out as Saturn, which gets much less sun than our moon. Thus the "no stars in photos" argument about Apollo holds no water. Even in a backyard telescope, if you look at Saturn, its brightness will wash out all but the very brightest of nearby stars because your eye adjusts for Saturn's brightness, not star brightness. (One nearby "star" you may see is actually the moon Titan.) The New Horizons probe did pick up star images in Ultima-Thule images, if you look at the raw exposures, but Ultima-Thule is really far away from the sun, beyond Pluto. And it's a dark body, requiring sensitive camera settings. Note that some raw exposures from some probes will show streaks that may be mistaken for stars, but are actually cosmic rays. They are usually digitally removed from final versions. The boundary where planetary exposures will start to clearly show stars is roughly around Neptune's or Pluto's orbit. But processing may have to remove them because time-lapse and/or multiple exposures may be needed to properly capture dim planets and rocky bodies that far out. Any stars caught would otherwise look smeared or smugdy.

avar 7y ago

Because they choose not to take photos of the surrounding stars, and those that are visible they either photoshop out or process the images in such a way that they're not visible. There's a sibling comment saying it's due to the exposure, that's wrong. That's not how Hubble works, it's not just a giant digital camera in orbit. The "photo" you're looking at is a composite from tens or hundreds of other images, so to start with most of the pixels you're looking at are just black filler. You can see the black and white raw images at http://hst.esac.esa.int/ehst/#home http://hst.esac.esa.int/ehst/#home search for "SATURN" under "Solar System Objects" and sort by date. A lot of the Hubble images from June 20th, 2019 have stars, including some visible between the rings and Saturn. They were just edited out because showing them wasn't the point.

michelb 7y ago
Is there a good explanation/article about how they take/process these images? I would have liked it if they could have included a bit of text about why certain items were not in the picture/removed.
biot 7y ago
Are those stars? The “iduy37thq” image [0], for example, has various star-like points of light on top of the planet itself in addition to appearing in the background. [0] http://hst.esac.esa.int/ehst-sl-server/servlet/data-action?RETRIEVAL_TYPE=PRODUCT&ARTIFACT_ID=iduy37thq_flt.jpg http://hst.esac.esa.int/ehst-sl-server/servlet/data-action?R...
- Ididntdothis 7y ago
  This look like the noise I get from my camera when I take very long exposures (> 10 minutes). The sensor starts heating up and producing these dots.
- xioxox 7y ago
  No they're probably not (I'm an astronomer). They're likely cosmic rays. When I've used Hubble data, then the processing uses multiple images to remove the cosmic rays (which aren't in common between images).