|T O P I C R E V I E W|
|LM-12||Apollo 11 frame 5924 and Apollo 17 frame 20463 are two Earth photos taken during EVA activities. You can tell by looking at the Earth terminator that the two landing sites are at different latitudes.|
I do not see the Reseau numbers on some of the Earth photos that Gene Cernan took. Perhaps it was an awkward angle, so I suspect that Cernan may have held his camera upside down or sideways to take those shots, including:
- frames 20957 to 20961 at Station 2
- frames 20465 and 20466 at the flag
- frame 20471 at the rover
|Headshot||I believe that the latitude of a lunar landing site can be roughly determined by the altitude of the Earth above the lunar horizon, e.g. the Earth would be on the horizon at the Moon's poles and be almost overhead when viewed from the lunar equator.|
I am not certain that the Earth's terminator has any bearing on the latitude of a lunar landing site, although it might be used to determine the difference in longitude between two different landing site.
Someone help us out with this.
|schnappsicle||You are correct on both counts. The earth goes through phases just like the moon does when viewed from earth, but unlike the moon, the earth stays roughly in the same spot in lunar sky at all times.|
|LM-12||Using Apollo 17 frame 20961 as an example:|
It would seem to me that (hypothetically) if someone was standing on the lunar equator when Cernan took that photo, they would see a horizontal Earth terminator. And someone standing on the lunar north or south pole would see a vertical Earth terminator.
Is that correct?
|One Big Monkey||This superb analysis takes the idea a step further!|
|Headshot||Yes LM-12, your reasoning is correct also. The angle of the Earth's terminator would vary by latitude as well.|
It is best to measure the angle of the terminator during half-Earth, when the terminator is a straight line. Despite what that excellent video shows, when the Earth is gibbous there is some subjectivity to determining the terminator angle.
|Glint||The angle of the terminator primarily varies by season. The seasons are caused by the earth's axial tilt.|
|LM-12||Frame 9189 is a LM and Earth view from the lunar surface on Apollo 14.|
None of the Apollo 15 and Apollo 16 Hasselblad photos taken on the lunar surface seem to show the Earth. That is a surprise. Can you find any?
|LM-12||I take it from the "superb" Earthrise video that One Big Monkey posted above that (1) the angle of the Earth's axis relative to the lunar horizon changes with latitude and can be used to determine lunar latitude, and (2) the elevation of the Earth above the lunar horizon changes with longitude and can be used to determine lunar longitude.|
So, if one can do all the calculations, the (approximate) location where an Earth photo like 20961 was taken can be determined from the photo alone? Amazing.
|LM-12||The view of Earth in the Apollo 11 emblem is wrong for where they landed. And when they landed also, I believe.|
Originally posted by LM-12:
The view of Earth in the Apollo 11 emblem is wrong for where they landed. And when they landed also, I believe.
It also needs to be rotated 90 degrees. I believe Mike Collins has owned up to his astronomical error.
|LM-12||"... wrong for where they landed" is the 90 degree error.|
An Earth view like frame 5924 should be on the emblem: upper half in sunlight with north pole at right. When Apollo 11 landed at 4:17:39 p.m. EDT, the eastern part of North America should have been visible in the sunlit half.
|Robert Pearlman|| |
quote: From "Carrying the Fire" by Collins:
Originally posted by moorouge:
I believe Mike Collins has owned up to his astronomical error.
I added a small earth in the background and drew the sunshine coming from the wrong direction...
|LM-12||Where would you have to be on the moon and when would you have to be on the moon to see the Earth view in the Apollo 11 patch?|
My guess is in the northwest quadrant of the moon near the lunar north pole, on a waning crescent moon.
|LM-12||The sunlight direction in the Apollo 14 mission patch is also incorrect.|