Illustration of the Apollo 11 Flight Path with labels and stages.

Howdy, this might be an odd question, but I'm using whatever information I gather here to help write an alternate universe version of the 1950s through 1980s. Due to some convoluted plot contrivance involving several delays to the moon landing, the very last pass behind the moon the Apollo crew takes place during a lunar eclipse. Now, I unfortunately don't have access to any simulation software, so I'm not sure what that would look like to them! How much of the lunar surface would the crew be able to see in passes that occur beforehand, and what does the phenomenon look like from space? Do we know what it might look like? Time is not of the essence, but I still need to know these details before writing this particular section of the story.


1 Answer 1


Lunar eclipses occur when the moon is full. When the moon is full, the far side of the moon is unlit. With neither the Sun nor the Earth in the sky, the only ambient light would come from stars, and this is not bright enough to see anything by. The moon would look completely black. The fact that a lunar eclipse is happening is largely irrelevant. The far side would be unlit during any full moon.

The near side of the moon would be lit by light refracted around the Earth. This would be bright enough to see the moon surface. It may be bright enough to read by. The exact brightness would depend on lots of unpredictable factors such as the amount of volcanic dust in the stratosphere. It would certainly be red just like we can see the moon during a lunar eclipse, so would the astronauts orbiting it.

In previous passes the Earth would at most partially cover the moon and the nearside surface would be well lit. The far side would be unlit and dark.

In fact the landing happened when the moon was just less than half full and so much of the far side would have been well lit.

  • 1
    $\begingroup$ Shouldn't the moon had a dim red tinge due to Rayleigh scattering? That's why we see the moon as a dim red during a total lunar eclipse. $\endgroup$
    – User24373
    Commented Nov 10, 2018 at 0:49
  • $\begingroup$ You would, if you were on the near side of the moon. But on the far side you can't see the Earth. $\endgroup$
    – James K
    Commented Nov 10, 2018 at 7:02
  • $\begingroup$ Oh I apologise, I should have been more clear, I meant that they would cross Earth visibility as the lunar eclipse was happening. Would it be the same? $\endgroup$
    – 916
    Commented Nov 10, 2018 at 20:17
  • 1
    $\begingroup$ Re the last sentence: And the total blackness (no sunlight, no earthlight, only starlight) was experienced as well for some part of the orbit (judging by this image, for about one quarter of the orbit) $\endgroup$ Commented Nov 11, 2018 at 14:40
  • $\begingroup$ Little pedantic note. The reddening of the moon as seen orbiting it is less than that as seen from earth. In the latter case Rayleigh sc. happens "twice" (more than twice doing the mathematics). $\endgroup$
    – Alchimista
    Commented Dec 24, 2018 at 12:30

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .