Wednesday, January 4, 2017

SearchResearch Challenge (1/4/17): The phases (and more!) of the moon

On January 1st, the moon was glorious on the horizon... 

... there it was... a beautiful slender crescent that hung in the western night sky just after sunset.  

Not my photo, but very similar to what I saw on Jan 1, 2017. P/C NASA

I spent a bit of time in rapt contemplation, and then started wondering... 

The US sent six missions to the moon (Apollo 11, 12, 14, 15, 16, 17).  And I remember reading the location of each landing, and then looking at the moon to locate exactly where the landers were located. Once upon a time, I knew the major craters of the Moon very well--I knew their shapes and locations like the back of my hand.  

Apollo 11 astronaut and foot pad of the lander.  P/C NASA

We all know that the Moon is a big sphere.  But it didn't occur to me until just now that the landings all just happened to be on a part of the Moon where I could see them?  Was this just clever publicity and mission planning to make their landing spots visible to the public?  

Once you get curious about something, it's hard to stop.  This line of thinking leads me to our Challenges for the beginning of 2017.  Can you figure them out? 

1. If you look at a map of the Apollo landing sites, they're all visible from Earth--none are on the back side (that is, the side of the moon that faces away from the Earth).  Why were all of the landing sites on THIS side?  (You'd think the back side would have been more interesting. Why didn't we go to the back side?
2. Every so often I'd sketch out the moon as I saw it in the night sky.  Once, when I was looking at several of my sketches together, I noticed that some of the craters on the Moon's edge seemed to be in slightly different places. Huh? I know that the Moon always has the same face pointed to us, but when I looked at my sketches, it would seem that it's not always exactly the same face--especially near the edge. Why would the Moon's face be slightly different during different times of the lunar month? Is it always showing us exactly the same face at all times?  

Both of these questions require a bit of thinking (rather than just search skills).  You'll need to do a bit of research and critical thinking to get to the answers.  

Can you answer these Challenges about the Moon?  

Search on, in the spirit of the Apollo missions!  


  1. 1) All the missions were to the near side due to the lack of communications to the far side of the moon. Also, the near side was mapped in much better detail, making a landing easier to plan.

    The communication part I pretty well knew reading the question. I also did a quick search for "apollo mission near side" and one of the results mentioned the mapping issue, which also makes pretty good sense.

    2) The moon librates (wobbles) in its orbit, showing slightly more than 50% of its surface. Again, knew this off the top of my head. A quick search for "moon libration" returns a link to which puts the number at about 59%.

  2. Good day, Dr. Russell and everyone.

    Very interesting topic and so much to learn and find. Doing a quick SRS found:

    [why we only see one side of the moon]

    why is the dark side of the moon, as it’s known, so elusive to the Earthbound?

    “The moon is tidally locked to the Earth", spherical, but not a perfect sphere. Includes animated video

    Since the Moon's orbit is elliptical, and not circular, the speed of its orbital travel increases and decreases depending on how close it is to our planet

    Earth's gravity causes tides on Moon deforming it like a melon

    [Why Apollo missions never went to dark side of the moon] and ["Apollo missions" around(3) dark side of the moon]

    Which side of the Moon did the Americans land on: the "dark side" or the "other side"?

    They landed on the near side because :

    A: It was much better known - they had maps of the entire near side to large scale. We didn't know what the far side looked like at all before the lunar missons

    B: Radio communication with Earth.

    They landed at partial phase, not full phase. Because when the sun was directly overhead it would be too

    Fast Answers

    1. Why were all of the landing sites on THIS side?
    A: This side is better known and had maps. Plus is the one we always see due to Tidal lock. Plus in the other side communications were not possible

    2. Why would the Moon's face be slightly different during different times of the lunar month?
    Due to its shape and also tidal lock. We see the same face but not same stage. And as we are close or far moon shape has variations and that is why the craters on the Moon's edge seemed to be in slightly different places.

    Will be back with more and also I'll re-confirm my findings

    1. [Apollo landings different views]

      Photos: New Views of Apollo Moon Landing Sites

      [Moon landing site visible from earth]

      How to See All Six Apollo Moon Landing Sites

      WHAT WERE THE FIRST LUNAR LANDINGS? The Soviet Luna 2 probe, the first man-made object to land on the Moon. Sept. 14th, 1959...The first US spacecraft to impact the Moon was the Ranger-7 probe on July 31st, 1964...

      [how were the Apollo landing sites chosen]

      The six landing sites were chosen to explore different geologic terrains.

      How were the landing sites of Apollo missions determined? Final site choices were based on the following factors:...

      [free return trajectory meaning] to know what that means.

      [moon landing site visible from earth changes moon stages]

      15 Questions about the Moon Landings Although the average person might inhale about 100 l of air per hour (so 2400 l per day), only 560 l of oxygen is consumed per day.

    2. Another new link with new information about the Moon. Once again, Dr. Russell and SRS creates a Challenge and in that week or few ones later new discoveries, news or information arrives to the World.

      Researchers Suggest New Theory for the Moon’s Origin

  3. 1. Before Searching I figured that it would very dark and very cold all the time. That there would no communication possible with Houston from back there. The front side was quite well known and so decent spots to land were plannable. So:

    [apollo missions did not land on the far side because] finds

    HAs a nifty map of all the landing sites too
    Dark side is 'radio dark' got it. No communication 24/7. Not neccesarily unlit though.
    We see a bit to either side because of Lunar Libration.

    SAME site: Mark Adler NASA JPL System Engineer and Project Manager says: They landed on the side with light shining on it at the time, during daytime, which lasts for two weeks. THey went to the near side so they could see to land, see what they were doing, take good pictures, and not be too cold.

    2. Same Quora site explains this: 'lunar libration' due to the slight rocking of the moon north/south and east/west our view of the 'edges' changes slightly thus we can actually see about 59% of moon surface.

    THis was great.

    jon tU who is moonstruck quite often when moon rises across Salish Sea and lights up the water

  4. After the Big Search I looked up Far Side Cartoon Gallery [images] What a delight they are. jon tU

  5. Replies
    1. Thanks Remmij for the links and photo. I didn't know about Selenographic coordinates. Searching for [Selenographic coordinates examples] found interesting things like [ Terminator Moon] and the [Apollo landing sites coordinates]

      Sadly, lost my links for the post due to not checking if I was logged.

    2. Hello Remmij! Thanks for the links. Moongiant is very good.

      Why Moon looks red?

      [Moon Camera 24 hours]

      Moon Super Zoom

    3. This video was suggested by YouTube. I haven't visited all the links posted here, so hope is not posted already.
      Why we can't see Landers from the Earth?

  6. the 2nd image…
    Buzz Aldrin prior to improvising the broken circuit breaker button… being able to adapt on the fly…
    Buzz Aldrin
    … found a higher-res image without the cropping… something seems off…
    move along, nothing to see here, move along…
    Here Men from the Planet Earth First set foot upon the Moon July 1969 A.D. We came in Peace for all Mankind
    on the lander leg
    more background

  7. Q1) Anne and Deb here. We started off this search thinking about this question and speculated that it may have had something to do with temperatures and/or safety. We then did a search using the terms We got many results and got these answers on the site Quora - We didn't think this was definitive enough so we did an advanced search limiting our seach to .gov sites and got this result Operational Constraints on Landing Sites It gives a very detailed explanation of why the landings needed to be on the near side - radio communications was key as was having some knowledge of the topography and much more was known about the near side then the far side. This article also points out to how the site was selected -
    They definitely wanted to know as much about the site as possible and the near side was what they had information on.

  8. Q2) Well the Quora site introduced us to the term libration (hmm and that so much like library - don't think they are related but we will go check the OED to see if there is a relation).We looked up the term and it is defined as an apparent or real oscillation of the moon, by which parts near the edge of the disc that are often not visible from the earth sometimes come into view. And that seems to be the answer - the moon wobbles a little so at times you see more or less. According to we usually see 50% of the moon's surface but at times we can see as much as 59%.