by alter-ego » Sun Sep 16, 2018 5:10 am
Pat42 wrote: ↑Thu Sep 13, 2018 2:12 pm
...
Btw, there is a fault on the video on July 27th, around 20 UTC. The lunar eclipse is missing !
At first glance that seems to be true. It is not evident from the description that LRO did
not take those pictures as real-time snapshots. In fact, it's likely there is no image in that video that was acquired in 2018. Probably all the lunation
animations (2011 to present) were derived from the Wide Angle Camera (WAC)
near-side mosaic made in 2011 from data (including South-up versions
![Smile :)](./images/smilies/icon_smile.gif)
) The WAC acquires a 60km-wide swath of images (at 50km altitude that's about a 114° field of view!). At that resolution about 600,000 images are required to cover a single hemisphere!
You can see that over a full hemisphere, it's not possible for the LRO to capture a lunar eclipse. Given the mosaics are likely many years old, you could say the images are "faults". A lot of calculations and morphing went into those images, but rest assured, though, the representations are very accurate. However,it would have been better to add a sentence in the description stating the images are not snapshots but instead are mosaics built from LRO WAC images taken over the years.
[quote=Pat42 post_id=285778 time=1536847926]
...
Btw, there is a fault on the video on July 27th, around 20 UTC. The lunar eclipse is missing !
[/quote]
At first glance that seems to be true. It is not evident from the description that LRO did [i]not [/i]take those pictures as real-time snapshots. In fact, it's likely there is no image in that video that was acquired in 2018. Probably all the lunation [url=https://svs.gsfc.nasa.gov/Gallery/moonphase.html]animations[/url] (2011 to present) were derived from the Wide Angle Camera (WAC) [url=http://lroc.sese.asu.edu/archive/popular_downloads]near-side mosaic[/url] made in 2011 from data (including South-up versions :)) The WAC acquires a 60km-wide swath of images (at 50km altitude that's about a 114° field of view!). At that resolution about 600,000 images are required to cover a single hemisphere!
You can see that over a full hemisphere, it's not possible for the LRO to capture a lunar eclipse. Given the mosaics are likely many years old, you could say the images are "faults". A lot of calculations and morphing went into those images, but rest assured, though, the representations are very accurate. However,it would have been better to add a sentence in the description stating the images are not snapshots but instead are mosaics built from LRO WAC images taken over the years.