[HN Gopher] Mercury's shadowy North Pole revealed by M-CAM 1
       ___________________________________________________________________
        
       Mercury's shadowy North Pole revealed by M-CAM 1
        
       Author : divbzero
       Score  : 38 points
       Date   : 2025-01-10 18:34 UTC (4 hours ago)
        
 (HTM) web link (www.esa.int)
 (TXT) w3m dump (www.esa.int)
        
       | varjag wrote:
       | Absolutely love the ESA Like button in the article. Conveys the
       | feeling it's designed by a flight instruments engineer rather
       | than a social media frontend person (make sure to click it
       | twice).
        
       | fluxflexer wrote:
       | I would have expected a larger crater for Tolkien..
        
       | bragr wrote:
       | >M-CAM 1 took this long-exposure photograph of Mercury's north
       | pole
       | 
       | I'm curious how this works. The dynamic range between the sunlit
       | parts and the dark portions must be huge at that distance from
       | the Sun. Anyone have the technical details on the camera or post
       | processing they use to achieve this? Is it really a long exposure
       | or is it a series of photos at different exposures stitched
       | together?
       | 
       | Edit: details at the bottom seem to imply a single photo, but
       | that "long exposure" really isn't that long
       | 
       | >This image of Mercury's surface was taken by M-CAM 1 [...] using
       | an integration time of 40 milliseconds.
        
         | therealfiona wrote:
         | Integration implies multiple pictures taken and stacked. This
         | is how we do deep sky astrophotography on our back yards.
        
           | fecal_henge wrote:
           | I think this is their terminology for exposure time. The
           | sensor is integrating charge from incident photons during
           | this period. Of course the image could be stacked also!
           | 
           | Edit: the sensor is integrating CURRENT. Charge is the
           | integral!
        
           | tejtm wrote:
           | Integration over time and integration over bit fields are
           | both ways we do deep sky astrophotography. Integration over
           | time is used to collect more photons without saturating
           | sensor wells and integrating bit fields (stacking) is used to
           | increase signal to noise
        
         | car wrote:
         | Wondering same. If my math is right, this was a 1/25 sec.
         | exposure. (40/1000)
        
         | dylan604 wrote:
         | If you're thinking that long exposure automatically means
         | something longer than 1 second, it might not mean long exposure
         | to you.
         | 
         | I'd guess this is a fixed aperture system where the main way to
         | control the exposure is with shutter speed. But for images
         | taken in bright sunlight, you can use shutter speeds 1/250,
         | 1/1000, 1/2000, or even higher type numbers. In those terms, 40
         | milliseconds is 10 times slower/longer than 1/250.
         | 
         | So for the M-CAM 1 system, 40 milliseconds could be an
         | extremely long exposure
        
       | ahazred8ta wrote:
       | With labels describing the surface features:
       | https://www.esa.int/ESA_Multimedia/Images/2025/01/Mercury_s_...
        
       ___________________________________________________________________
       (page generated 2025-01-10 23:00 UTC)