APOD: Earthrise (2015 Sep 06)

Comments and questions about the APOD on the main view screen.
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APOD: Earthrise (2015 Sep 06)

Post by APOD Robot » Sun Sep 06, 2015 4:11 am

Image Earthrise

Explanation: What's that rising over the edge of the Moon? Earth. About 47 years ago, in December of 1968, the Apollo 8 crew flew from the Earth to the Moon and back again. Frank Borman, James Lovell, and William Anders were launched atop a Saturn V rocket on December 21, circled the Moon ten times in their command module, and returned to Earth on December 27. The Apollo 8 mission's impressive list of firsts includes: the first humans to journey to the Earth's Moon, the first to fly using the Saturn V rocket, and the first to photograph the Earth from deep space. As the Apollo 8 command module rounded the farside of the Moon, the crew could look toward the lunar horizon and see the Earth appear to rise, due to their spacecraft's orbital motion. Their famous picture of a distant blue Earth above the Moon's limb was a marvelous gift to the world.

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Re: APOD: Earthrise (2015 Sep 06)

Post by DL MARTIN » Sun Sep 06, 2015 7:07 am

The impact of seeing the Earth in isolation affirmed the notion that, indeed, there is no free lunch.

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Re: APOD: Earthrise (2015 Sep 06)

Post by Boomer12k » Sun Sep 06, 2015 8:28 am

It was a "different" world back then...not better....just different, or similar problems...but not like today.

BUT STILL A VERY PRETTY BLUE MARBLE...

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Re: APOD: Earthrise (2015 Sep 06)

Post by ceelias » Sun Sep 06, 2015 9:00 am

Like most of us, I've seen that photo before, but never with the colors so vivid. thanks for digging this out of the archives. It is appreciated.

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Re: APOD: Earthrise (2015 Sep 06)

Post by saturno2 » Sun Sep 06, 2015 10:19 am

Beautiful.

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Re: APOD: Earthrise (2015 Sep 06)

Post by DrJoeS » Sun Sep 06, 2015 12:34 pm

This is a classic photo. I remember seeing it for the first time. I remember the excitement of Apollo leading up to July 1969. Great throwback shot.

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Re: APOD: Earthrise (2015 Sep 06)

Post by Coil_Smoke » Sun Sep 06, 2015 4:05 pm

What land masses do you see on Earth in this image? My guess: Eastern USA, including Cape Hatteras + Eastern South America.

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Re: APOD: Earthrise (2015 Sep 06)

Post by MarkBour » Sun Sep 06, 2015 10:42 pm

Coil_Smoke wrote:What land masses do you see on Earth in this image? My guess: Eastern USA, including Cape Hatteras + Eastern South America.
We are indeed used to seeing the Earth in our mind's eye, in a particular conventional orientation.

Actually, in this photo, we are seeing West Africa moving towards the sunset terminator. I believe the South Pole is visible near the edge of the disk (at about 5/6 pi in standard radial coordinates, if you will) while the North Pole is cloaked in the continual darkness of December, and would be out of view anyway, a little behind the edge of the disk.

I could not have figured this out on my own, but:
https://commons.wikimedia.org/wiki/File ... thrise.jpg
gives some of these facts, and a lovely set of tools on the USNO website at:
http://aa.usno.navy.mil/data/docs/earthview.php
are fun to play with. If you plug in 1968, December 24, 16:40 UT1, you can get the views.
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Re: APOD: Earthrise (2015 Sep 06)

Post by Boomer12k » Sun Sep 06, 2015 10:47 pm

Coil_Smoke wrote:What land masses do you see on Earth in this image? My guess: Eastern USA, including Cape Hatteras + Eastern South America.
My Guess was Australia for the land mass....but we are BOTH WRONG.... from Wikipedia about the photo, and land mass, and orientation of photo...

"The as-published photograph shows Earth:

Polar orientation: south to left, north to right (Antarctica at 10 o'clock) (from me...so tilt your head to the RIGHT...now the land mass is AFRICA!!! back to description.)
Equator: center, running westward toward top right-hand corner
Nightfall terminator crossing the African continent (lightish region to left is Namib Desert, Namibia; to right is Western Sahara/West Africa)
Rotated clockwise approximately 135° from our typical North/South-Pole-oriented perspective
"

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Re: APOD: Earthrise (2015 Sep 06)

Post by ta152h0 » Mon Sep 07, 2015 12:04 am

" Man, we are really out there ! "
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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Mon Sep 07, 2015 1:13 am

Can anyone identify any of the lunar craters? I'm afraid I cannot. Based on the time and orientation of the shot, I estimate that Apollo 8 must have been over the southern part of Mare Smythii, just into the "far side", ~93&deg; East, ~8&deg; South, with the shot looking westward and into the "near side", to the lunar horizon at about 67&deg; East.

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Re: APOD: Earthrise (2015 Sep 06)

Post by Guest » Mon Sep 07, 2015 3:42 am

47 years!?! (sigh) We should have a full time inhabited colony on the lunar surface by now. But Nixon killed Apollo since it was JFK's pet project. And various presidents have tried to get us back on course to the Moon, but now NASA has become the "Do Nothing Agency" preparing humans to perform Circus stunts like going to asteroids or, oh yes... Mars. Go directly to Mars. Do not stop at the Moon and collect invaluable knowledge and experience. Yes, I remember this picture very well. I remember when it was our destiny.

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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Mon Sep 07, 2015 4:56 am

Nitpicker wrote:Can anyone identify any of the lunar craters? I'm afraid I cannot. Based on the time and orientation of the shot, I estimate that Apollo 8 must have been over the southern part of Mare Smythii, just into the "far side", ~93&deg; East, ~8&deg; South, with the shot looking westward and into the "near side", to the lunar horizon at about 67&deg; East.
Not that I can suddenly answer my original question, but I've just seen a re-creation video:
Click to play embedded YouTube video.
... that puts Apollo 8 closer to 114&deg;E, 11&deg;S, at an altitude of 110 km, at the time the APOD was taken. That means the distance to the lunar horizon is about 630 km [contrary to what Wikipedia says], which would put it at about about 93&deg;E.

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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Tue Sep 08, 2015 12:21 am

The combination of the video from my last and the online LROC Quickmap, has allowed me to refine my numbers and identify two of the prominent craters in the foreground, as shown in my annotated version:
Earthrise_Apollo8_reduced_labelled.jpg
Note that Debus has a diameter of about 20 km and the distance along the lunar surface, from the bottom of the frame to the horizon is about 250 km. I figure the Moon must have been close to its maximum westward longitudinal libration (7 to 8 degrees), at the time of the APOD.
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Re: APOD: Earthrise (2015 Sep 06)

Post by alter-ego » Tue Sep 08, 2015 3:56 am

Nitpicker wrote: ...
Note that Debus has a diameter of about 20 km and the distance along the lunar surface, from the bottom of the frame to the horizon is about 250 km.
I agree with the craters.
The APOD primarily shows craters that are members of Pasteur (U, T) and Debus (U is the lower right crater, or the one connected to it on very lower-right corner). Mostly being smaller craters and greatly foreshortened, identification is difficult. I found Borman's B&W image (16:38:45) was the best for crater identification. The elevation map below shows the entire region with Apollo 8's location and image FoV for Borman's shot. The APOD image was taken about 1 minute later (~90km change in orbital position) and 3 common craters can be picked out.
[attachment=1]Apollo 8_Borman B&W Earthrise_163845 UT.JPG[/attachment]
[attachment=0]Borman Earthrise - Apollo 8.JPG[/attachment]

Regarding the horizon distances, I believe the mountain range between Pasteur and Ganskiy limits the bulk of "horizon" distance for both images, Borman's and the APOD. From Borman's location, the horizon distance ~560km. From the APOD's bottom edge, the horizon distance more likely ranges between 120km to 200km. I don't think it's possible to have the lower-elevation craters (e.g. Ganskiy) in either image, but there may be a few of the longer-range mountains peaking through. So roughly speaking, I estimate the horizon is at longitudes 97°E to 100°E.
I don't know if it's been stated earlier, but it's worth mentioning the terminator is at 30°E.
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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Tue Sep 08, 2015 5:53 am

Yes, you are probably (just) right about the mountains forming the horizon, thereby making it a bit closer. My calculations were based on a perfectly circular Moon, an Earth size of almost 2 degrees, and the stated coords of the spacecraft (from the re-creation video). It was at least good enough to identify the craters. I should have stopped there. :ssmile:

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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Wed Sep 09, 2015 6:39 am

The area within the red polygon, represents my best estimate of the visible lunar area in the APOD (including some of the lower elevations that aren't visible). Note that each grid square is about 30x30 km in size. Also note that Pasteur U and V are labelled slightly differently than in alter-ego's map. (Credit for my image, apart from the red polygon, goes to the LROC Quickmap site.)
apollo_8_earthrise_viewshed.jpg
Edit: I don't know why LROC calls it Ganskiy Hansky, but I find it rather fetching.
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Re: APOD: Earthrise (2015 Sep 06)

Post by alter-ego » Thu Sep 10, 2015 6:03 am

Nitpicker wrote:The area within the red polygon, represents my best estimate of the visible lunar area in the APOD (including some of the lower elevations that aren't visible). Note that each grid square is about 30x30 km in size. Also note that Pasteur U and V are labelled slightly differently than in alter-ego's map. (Credit for my image, apart from the red polygon, goes to the LROC Quickmap site.)
Edit: I don't know why LROC calls it Ganskiy Hansky, but I find it rather fetching.
Although I agree choosing the center of the craters you've labeled makes sense, the official crater coordinates typically don't align with the centers for some reason. For U & V, the coordinates correspond to the approximate boundaries of two connecting craters - I don't know why the coordinates are off like that. I wondered whether positions were based on some feature characteristic or a weighting of some sort. I have a hard time believing the coordinates have errors that large.

For Ganskiy (Hansky), the Nasa Catalog of Lunar Nomenclature lists the crater as Hanskiy. Probably a pronunciation based spelling. The crater is named for Aleksey P. Ganskiy.
To quote Wiki: "This crater is sometimes listed as "Ganskiy", "Hansky" or "Hanskiy"."

You can call me Hanskiy, or you can call be Ganski, or you can call me Ganski Hanskiy, or you can call me Hansky Gansky ... but ya doesn't hafta call me skanky!
Click to play embedded YouTube video.
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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Thu Sep 10, 2015 6:33 am

alter-ego wrote:Although I agree choosing the center of the craters you've labeled makes sense, the official crater coordinates typically don't align with the centers for some reason. For U & V, the coordinates correspond to the approximate boundaries of two connecting craters - I don't know why the coordinates are off like that. I wondered whether positions were based on some feature characteristic or a weighting of some sort. I have a hard time believing the coordinates have errors that large.
But your map's "V" is officially "U" and your "U" has not been assigned an official letter. "Pasteur V" is the one coloured red/yellow in your map, just NW of the crater you have labelled "V". (The discrepancies in the official coords are at least within the craters.)

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Re: APOD: Earthrise (2015 Sep 06)

Post by alter-ego » Fri Sep 11, 2015 5:04 am

Nitpicker wrote: But your map's "V" is officially "U" and your "U" has not been assigned an official letter. "Pasteur V" is the one coloured red/yellow in your map, just NW of the crater you have labelled "V". (The discrepancies in the official coords are at least within the craters.)
Yup. I missed that. When I clicked to elevation mode the labels went away. Manually putting labels on ungrouped mosaic compositions can lead to errors.

What you say about coordinates lying within the craters is not true. In the picture below, the little dots next to the letters mark the official coordinates. H,G (white cursor),M,R,V and Z are definitely outside the assigned crater. Many are on the rim. V is actually inside the little crater. I'm thinking the official coordinates (also in Wiki) may simply have errors. The NASA catalog was published in 1982, and apparently the coordinates are "estimates". It all just seems out of place (no pun) since we are used to very precise data these days. It's clear the coordinates could be updated today avoiding any confusion or ambiguity.
Pasteur Lables.png
NASA Catalog of Lunar Nomenclature wrote: Acknowledgments The initial versions of the computer-printed lists
of craters were prepared by the late Dr. Leif E. Andersson, who was also
responsible for estimating coordinates for all the listed farside craters
as well as for many in the nearside limb regions
. He also computed the
diameters of these craters from measurements made by LPL staff on Lunar
Orbiter photographs, and wrote the preliminary version of the accompanying
explanation of the crater listings. I thank Ed Rains and John Spencer
for performing various checks and for incorporating several changes and
updates into the lists, and the latter for producing the computer-printed
versions reproduced here. I also thank Dan Kinsler, late of the Lunar
and Planetary Institute, for valuable assistance throughout most phases
of this project, and especially for his review of the new farside letter
designations, which resulted in several improvements being made.

This work was supported by NASA grant NGL 03-002-191


Ewen A. Whitaker
Tucson, September 1981
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Re: APOD: Earthrise (2015 Sep 06)

Post by Nitpicker » Fri Sep 11, 2015 5:58 am

Hmmm, yeah, I only checked a few craters. However, in your latest image, it appears that the translation errors are fairly consistent. Clear evidence of massive moonquakes since 1982 ... pause ... not.

I am not sure which coordinates are officially classified as official, but the ones that the LROC Quickmap site use to label the craters, seem to be pretty good. The data for the nomenclature used (which I assume includes the coords) is stated to be provided by the USGS Gazetteer of Planetary Nomenclature. It is hard to imagine that the LROC site is not using ortho-rectified images. But I can imagine that smallish errors in the data from 1982, especially from the far side, might not be considered too serious by too many.