Moon-Earth Position: Apollo 8 Photo Examined

In summary, the conversation discusses the position of the Earth in the sky when observing from the moon, with a specific reference to a photo in the book "The Rough Guide to the Universe" by John Scalzi. The photo shows the Earth rising above the horizon of the moon, but the poster questions the accuracy of this depiction. Other posters suggest that the photo was likely taken from an orbiting spacecraft rather than the surface of the moon, and explain the brightness and darkness of the moon's surface during day and night. Finally, the conversation touches on the lunar libration effect, which causes a slight wobble in the moon's orbit and allows for slightly different views of the moon's surface.
  • #1
StephenPrivitera
363
0
Since the moon always has the same side facing Earth, shouldn't the Earth always be in the same position in the sky when observing from the moon? There's a photo taken by the Apollo 8 crew in a book I have that claims the Earth is rising above the horizon of the moon. The book is "The Rough Guide to the Universe" by John Scalzi in case you have it and want to look it up (page 197). It struck me as wrong. Let me know what you think.
 
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  • #2
I haven't seen the picture, but could it be seeing the Earth at sunrise on the earth?
 
  • #3
Originally posted by StephenPrivitera
Since the moon always has the same side facing Earth, shouldn't the Earth always be in the same position in the sky when observing from the moon? There's a photo taken by the Apollo 8 crew in a book I have that claims the Earth is rising above the horizon of the moon. The book is "The Rough Guide to the Universe" by John Scalzi in case you have it and want to look it up (page 197). It struck me as wrong. Let me know what you think.

I would think this is taken from the orbiting craft; not from the surface. I am not aware of any expeditions into the dark side of the moon...except of course by Floyd.
 
  • #5
It's a picture of a gibbous Earth with the lit limb facing upwards (above the horizon). I guess I'm having trouble interpreting the picture. Since the gibbous faces upwards doesn't that mean the Sun is above the horizon? Then it must be day on the moon, but the background of the picture is black. How can you have a picture of the Earth from the moon during the day on the moon without having a bright background? Is the brightness of the Earth day due to our atmosphere? If you were in empty space nearby the Sun (say, 1AU away), would it be bright like the day? Would you simply turn around to make it be night time? Whenever I picture space outside the Earth's atmosphere I picture darkness.

What is the "lunar Libration effect?"
 
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  • #6
Originally posted by StephenPrivitera
Is the brightness of the Earth day due to our atmosphere?

Yes. The parallel light rays from the sun get scattered once entering our atmosphere, thereby bouncing off lots of stuff and illuminating the whole area.

If you were in empty space nearby the Sun (say, 1AU away), would it be bright like the day? ... Whenever I picture space outside the Earth's atmosphere I picture darkness.

The sun would still appear bright like it does in our sky, but space would be black in other directions (except of course for the bright stars).

Check out some of the photos from the space shuttle or the Hubble telescope.

What is the "lunar Libration effect?"

As you know, the Moon keeps the same face toward the Earth. However, there is a slight wobble...you get to see a bit more (few degrees) on one side or the other from time to time...due to the Moon's slightly non-circular orbit.
 
  • #7
Originally posted by Phobos
The sun would still appear bright like it does in our sky, but space would be black in other directions (except of course for the bright stars).
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Could it be then that on the moon during the moon day the background appears black even though the sun in in the sky? From what I know, the moon has a very minimal atmosphere. That would explain the picture.
 
  • #8
Without any appreciable atmosphere to refract light rays from the sun, the moon sky will remain as black - essentially, deep space. The stars generally aren't visible in the photos because of brightness and contrast issues (ie, they are drowned out by the light of a lunar day).
 

1. What is the significance of the Apollo 8 photo of the Moon-Earth position?

The Apollo 8 photo of the Moon-Earth position is significant because it was the first time humans had captured an image of the entire Earth from space. This photo, known as "Earthrise," sparked a new perspective on our planet and its place in the universe.

2. How was the Apollo 8 photo of the Moon-Earth position taken?

The photo was taken by astronaut William Anders using a Hasselblad 500EL camera with a 250mm lens. The camera was mounted on the spacecraft's window, and the photo was taken on the fourth orbit of the Moon on December 24, 1968.

3. Can the Apollo 8 photo of the Moon-Earth position be recreated today?

Yes, the photo can be recreated using modern technology and satellites. However, the angle and perspective may not be exactly the same as the original photo.

4. What scientific discoveries were made from the Apollo 8 photo of the Moon-Earth position?

The photo helped scientists understand the Earth's fragility and the importance of preserving our planet. It also provided valuable data on atmospheric composition and weather patterns.

5. How did the Apollo 8 photo of the Moon-Earth position impact the future of space exploration?

The iconic photo inspired future space exploration missions and sparked a new interest in exploring the unknown. It also highlighted the potential for humans to travel to and explore other planets.

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