Moon
by John
I know that this blog is titled “johnsmachines”, but I do get interested in “other stuff” too.
I came across this video on YouTube yesterday. It runs for 4 hours.
The footage was shot by an amateur astronomer, through telescopes which anyone can buy. A 9.5″ Celestron reflector (Schmitt Cassegrain I think), and an 80mm Orion refractor.
I used to be an amateur astronomer, and still retain an interest. One of my worst decisions ever was to give away an Orion 10″ reflector about 10 years ago.
Anyway, back to the video. It shows the surface of the moon, concentrating on some interesting areas. Following are some screen shots. It is titled “Live Moon Surface Observation”. Worth a look. Suggest jumping to 28minutes and watch maybe 5 minutes, zooming in and out.
80mm refractor. Look at the protruberance in the top left crater. Looks like a clenched fist. That is really unusual. Impact craters often have a central spike, and it is thought that the moon has had volcanic activity in previous aeons. But there is no atmosphere to cause wind erosion, and no surface water. Just traces of ice in the depths of craters at the poles. So how could that shape have arisen? And look at the bottom right crater…. that rectilinear shape. Circular shapes are meteor impacts, in many case impacts upon impacts. So how do you explain straight lines like these?
The same craters through the reflector scope. Image reversed. Look closely at the areas surrounding the craters. Do you see the other rectangular and square shapes?
Close up of the fist. Pixellation appearing.
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Earth’s moon is strange.
It is the largest moon in the solar system relative to the parent planet.
It is much less dense than earth. (why? if it is made of the same rock). (5.51g/cm vs 3.34g/cm. Thought to be due to Earth’s metal core.)
It almost exactly blocks the disk of the sun during a lunar eclipse. Coincidence?
The other side of the moon always faces away from earth. Until the space program, no human had ever seen the other side of the moon. The other side, incidentally, is quite different from the side which we see. Much more cratered, no large flat areas. Presumably most meteors come from the direction away from the sun (because they are scooped up by the gravitational field of the sun).
One moon day is exactly the same length as a lunar month. It is the only moon in the solar system where this applies. That is why the other side of the moon always faces away from earth. Another coincidence? (correction. Pluto – Charon also exhibit this behaviour, so it is not unique, just unusual. Thought to be due to “tidal locking”- thanks Gene).
OK. I know. You came to this site to look at my machines, particularly the Trevithick dredger engine. I am still fiddling with small details which are not very photogenic, but necessary before I run it on steam. Currently hooking up the boiler feed pump.
I was intending to pull apart the pump to show you the components. It is more complicated than the exterior shows. Piston, O ring, 2 stainless steel balls, one spring. I machined that 3 way junction box from a gas fitting, adding the delivery union to the top. Nothing tested yet. I hope that it works!
johnsmachines 
John,
I cannot say much about the mysterious shapes, but as a physicist I can comment on the density and rotational period.
The lunar surface density is actually a little bit higher than the surface density on earth. However, the moon has relatively little in the way of a heavy iron core, so the average density of the moon is somewhat less than the average density of the earth. No real mystery.
The rotational period is also easily explained. Any rotation, moon or earth, induces tidal motions inside the body which help convert rotational kinetic energy into heat. The result is slowing of the rotation. Over a time span of several billion years the moon rotation has slowed to the point that the lunar day (referenced to the earth, not the sun) is now the same as the orbital revolution period. That means the tidal losses are now very low (not quite zero for other reasons) and the rotational period is stable.
The earth rotation is also slowing for the same reason, but the sun will be long gone before the earth day lengthens to a full year.
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Thanks for the clarification Gene. On further checking I see that Pluto-Charon exhibit the same tidal locking. My previous info was wrong about our moon being unique in this regard. The density difference is quite marked 5.51g/cm vs 3.34g/cm. Also not unique. I will correct the post. John
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