APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Comments and questions about the APOD on the main view screen.
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APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by APOD Robot » Tue Nov 04, 2014 5:08 am

Image Moon and Earth from Chang'e 5-T1

Explanation: Described at times as a big blue marble, from some vantage points Earth looks more like a small blue marble. Such was the case in this iconic image of the Earth and Moon system taken by the Chang'e 5-T1 mission last week. The Moon appears larger than the Earth because it was much closer to the spacecraft's camera. Displaying much of a surface usually hidden from Earth, the Moon appears dark and gray when compared to the more reflective and colorful planet that it orbits. The robotic Chang'e 5-T1 spacecraft, predominantly on an engineering test mission, rounded the Moon last Tuesday returned to Earth on Friday.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Boomer12k » Tue Nov 04, 2014 6:01 am

Awesome view....awesome achievement...looks like a bunch of highways and roads....or maybe "canali"? LOL....not really.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by ProbeSpace » Tue Nov 04, 2014 6:07 am

Just curious, why are the multitudes of stars among the Milkyway apparently not visible in so many of these otherwise high-resolution, highly-processed images taken from outer space?

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by geckzilla » Tue Nov 04, 2014 6:30 am

ProbeSpace wrote:Just curious, why are the multitudes of stars among the Milkyway apparently not visible in so many of these otherwise high-resolution, highly-processed images taken from outer space?
Earth and Moon are too bright. Anytime you see artistic representations of the Earth, Moon, or nearly any sunlit side of any planet in front of the expanse of the Milky Way, they're kind of wrong. You'd never be able to see the dim stars with the glare of a bright planet in view. Turn around to the darkness, wait for your eyes to adjust for a moment, and the stars will appear. Indeed, what you think of as being highly-processed is most likely minimally processed.
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Markus Schwarz » Tue Nov 04, 2014 8:47 am

ProbeSpace wrote:Just curious, why are the multitudes of stars among the Milkyway apparently not visible in so many of these otherwise high-resolution, highly-processed images taken from outer space?
Adding to what geck has said: This is the same reason why you couldn't see a firefly right next to the sun. You can have live view from the ISS. The cameras' sensitivities are adjusted such that you can see features of Earth, but the sky is pitch black because the stars are too faint.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Tue Nov 04, 2014 9:09 am

One of the best selfies ever taken.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Czerno o » Tue Nov 04, 2014 10:10 am

A nice photograph!
Nitpick: "usually hidden from Earth" (caption). Usually is an (unwelcome) understatement here, isn't it ?

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Markus Schwarz » Tue Nov 04, 2014 10:19 am

Nitpicker wrote:One of the best selfies ever taken.
Isn't a selfie a self-portrait? So it would require a picture of the spacecraft. Best selfie is this one, IMHO.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Tue Nov 04, 2014 11:48 am

Markus Schwarz wrote:
Nitpicker wrote:One of the best selfies ever taken.
Isn't a selfie a self-portrait? So it would require a picture of the spacecraft. Best selfie is this one, IMHO.
People on Earth instructed the cameras to take both photos. But the one from Mars shows the machine holding the camera, not the photographer on Earth.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by MargaritaMc » Tue Nov 04, 2014 12:20 pm

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
&mdash; Dr Debra M. Elmegreen, Fellow of the AAAS

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Ron-Astro Pharmacist » Tue Nov 04, 2014 6:06 pm

A great photo to see our worlds from a new perspective. It made me think of those points in space where gravity likes to balance itself. In trying to refresh my memory and re-attempt to understand them, I ran across a pretty good explanation.

http://www.haydenplanetarium.org/tyson/ ... f-lagrange

Wonder if we ever drag a good-sized asteroid to orbit the moon will it create new points or affect the old ones? I suppose this is one of the times when size matters but maybe technique can compensate. I mean – orbit the asteroid around the moon longitudinally equidistant to the Earth. :wink:
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by khbynum » Tue Nov 04, 2014 6:31 pm

I'll admit I'm not good with 3-dimensional relationships, but I assume that the Sun is essentially equidistant from Earth and Moon. So, they should be equally illuminated. Why does the Moon appear "fuller" than Earth?

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by geckzilla » Tue Nov 04, 2014 7:37 pm

khbynum wrote:I'll admit I'm not good with 3-dimensional relationships, but I assume that the Sun is essentially equidistant from Earth and Moon. So, they should be equally illuminated. Why does the Moon appear "fuller" than Earth?
They have enough angular separation that it does matter, as you have observed. I was able to quite easily recreate a similar set of illuminations using Universe Sandbox. I made the background gray so that the whole spheres of both bodies are visible.

Edit: To add further to this observation I would say that the position of the observer is of greater importance than the angular separation of the two bodies.
moon_earth_sim.png
Edit 2: Added simplified illustration of what is going on.
sun_moon_earth_chang_illustration.png
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Guest » Tue Nov 04, 2014 8:04 pm

I am under the impression that Chang'e 5 was a mission yet to launch. Is the spacecraft designation correct or is Wikipedia wrong?

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by geckzilla » Tue Nov 04, 2014 8:06 pm

Guest wrote:I am under the impression that Chang'e 5 was a mission yet to launch. Is the spacecraft designation correct or is Wikipedia wrong?
Not Chang'e 5. Chang'e 5-T1. http://en.wikipedia.org/wiki/Chang%27e_5-T1
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by khbynum » Tue Nov 04, 2014 8:59 pm

geckzilla wrote:They have enough angular separation that it does matter, as you have observed. I was able to quite easily recreate a similar set of illuminations using Universe Sandbox. I made the background gray so that the whole spheres of both bodies are visible.

Edit: To add further to this observation I would say that the position of the observer is of greater importance than the angular separation of the two bodies.
Thanks, geck, and thanks for running a simulation on it. I still can't wrap my head around the geometry of it, but as an ex-biologist I'm not going to argue with an astronomer on an astronomy site! It's a beautiful image and is now my wallpaper.

Edit: OK, you posted your "observers position" graphic after I replied to your original post. Now I understand. Thank you again.
Last edited by khbynum on Tue Nov 04, 2014 10:08 pm, edited 1 time in total.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by julianm3 » Tue Nov 04, 2014 9:59 pm

geckzilla wrote:
khbynum wrote:I'll admit I'm not good with 3-dimensional relationships, but I assume that the Sun is essentially equidistant from Earth and Moon. So, they should be equally illuminated. Why does the Moon appear "fuller" than Earth?
They have enough angular separation that it does matter, as you have observed. I was able to quite easily recreate a similar set of illuminations using Universe Sandbox. I made the background gray so that the whole spheres of both bodies are visible.
Easy enough to set this up in Kerbal Space Program :-)

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Wed Nov 05, 2014 1:12 am

Whilst geck's illustrations, above, help to understand the illuminations in the APOD, the following diagram gives a better sense of the vastness of the Sun-Earth-Moon system, as everything is drawn to scale. (I hope I haven't made any mistakes, apart from drawing the Earth and Moon orbits in the same plane, which is not quite correct. It may help to have two monitors.)
sun_earth_moon.png
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Ann » Wed Nov 05, 2014 1:30 am

Thanks for the diagrams and illustrations, Geck and Nit.

Anyone who takes a look at the illustration provided by Nitpicker should not be surprised that the United States has managed to send humans to the Moon, in view of the, comparatively speaking, unimpressive distance between the Earth and the Moon. Also no one should be surprised that there has been no attempt to send a human to Mars, in view of the fact that Mars, when it is closest to the Earth, is at least half as far away as the distance between the Earth and the Sun.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Wed Nov 05, 2014 1:42 am

I forgot to mention that at the time of the APOD, the Moon appeared as a waxing crescent from Earth (whilst it appeared in waning gibbous phase from Chang'e 5-T1, however briefly).

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by geckzilla » Wed Nov 05, 2014 1:53 am

So an artist and an engineer have both had their fun. Between the two of us, anyone visiting the thread should now be fully informed. ;)
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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by jambo » Wed Nov 05, 2014 1:55 am

Is the perspective representing earth as north up, so the circle is the north pole and the large white area is the south pole?

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Wed Nov 05, 2014 2:05 am

jambo wrote:Is the perspective representing earth as north up, so the circle is the north pole and the large white area is the south pole?
Not sure what you mean by the "the circle is the north pole", but yes, North is up more or less in the APOD. With the Sun south of the Equator, Antarctica is illuminated and the North Pole is in darkness.

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Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by Nitpicker » Wed Nov 05, 2014 2:14 am

Ann wrote:Anyone who takes a look at the illustration provided by Nitpicker should not be surprised that the United States has managed to send humans to the Moon, in view of the, comparatively speaking, unimpressive distance between the Earth and the Moon.
Actually, I'm impressed. Most Americans I've met seem to baulk at the 15 hour flight to Australia. :ssmile:

jambo

Re: APOD: Moon and Earth from Chang'e 5-T1 (2014 Nov 04)

Post by jambo » Wed Nov 05, 2014 2:19 am

Because of the circular design of the clouds, the N/S poles appear to me to be at an 11/5 o'clock orientation. But are you saying the north pole is in the shadow and not visible at all? Is there a continent or anything recognizable through the clouds?