Moon question

[Allan_L]

Does the Moon rotate on its axis?

Or is it a captured movement of the Earth's influence.

I know it always presents the same face to the Earth, but I believe there may be differences of opinion on this area of lunar physics.

Picture a leaf caught in a whirlpool. It may always present the same face to the centre of the whirlpool, but could you really say that leaf is rotating on its axis?

What do you reckon?

[Nesti]

I believe it rotates at the same rate as it revolves [around the earth]. According to modern genesis theories, Earth was hit by a large body. This blew a large chunk off which became the Moon. The spin rate was conserved (conservation of angular momentum) in the matter which formed the Moon. So the spin rate for the Moon and that of Earth should be similar.

As for this statement, "a captured movement of the Earth's influence"...the Moon is most definitely captured by the Earth's influence, likewise, the Earth is captured by the moon's influence. This extends to all matter - and energy - in the entire Solar System, Milky Way, all Galaxies...everything that has mass...and if you subscribe to Einstein's equations, that must include energy too (energy momentum tensor).

There is only one Spacetime and we are all embedded in it. It's features are governed by both the distribution of mass and energy as well as what that mass and energy are doing. Mass and energy literally create the spatial and temporal separation, but an "influence", from one body to another, is also governed by the degree of spatial and temporal separation (distance and time).

In modern jet engines, large sections may be thermodynamically coupled; you cannot affect one without affecting all coupled parts, even though they are not physically connected, and yet they spin freely. Likewise, you cannot change the mass, velocity, spin etc (the Energy Momentum Tensor) without affecting the spatial and temporal properties of Spacetime (the field), not just because they are balanced, but because they are the same system. Energy/Mass, and, Space/Time, are not separable, they are mutually supportive...you could almost say they are different properties of the same thing.

[michaellxv]

It rotate's on its own axis. Like the earth its axis of rotation is tilted from the plane of its orbit. This creates the libration which allows us to see more than half of is surface.

Interesting question.

[adman]

The moon does not spin on its axis at all....

Adam

[Nesti]

If you stood on the surface of the dark side of the moon, you would see the stars move, around and around...how is that not spinning body?

[bloodhound31]

Use your mobile phone on the desk like a toy car and drive it around and around in circles. Drive around in ever decreasing circles until you are spinning on the spot, rotating on an axis.

Just because you are driving around something, does not mean you are not spinning yourself. It just means you are moving in an orbital path as you are spinning. Look out the window of a real car doing the same thing, and you will notice the objects around you move around and around.

Now, hold your mobile phone on the desk and just draw circles with it, without turning it. It is just on an orbital path without spinning, and if you were inside a real car doing this, the view outside your window would not change.

Baz.

[wasyoungonce]

Shee's fella's is Tidal Lock (http://en.wikipedia.org/wiki/Tidal_locking).

[Nesti]

Forget what we see the Moon doing from the perspective of the Earth...what matters is what is seen from the perspective of the Moon itself...the Moon sees a reoccurring and revolving sky pattern. That is spin.

So, Baz, the Moon is like your mobile phone traveling in an orbital path, and we, at the circle's centre, only get to see one side of the mobile phone, while the rest of the universe gets to see all sides of the mobile phone (Moon).

Like Parallel Transport.

[Nesti]

:lol::lol::lol:

LOL...Tidal Lock is the phenomenon...so what causes Tidal Lock???

This'll be good...:lol:

[wasyoungonce]

Probably a natural energy level settling, an interplay of Newtons & Keplers laws of the bodies.

Each body exerts gravitational energy on each other..the bigger mass wins the smaller mass looses energy & attains a stable orbit.

Moon has a solid core and this may also add to the effect of tidal locking.:help:

[mswhin63]

They both, Moon spins on it axis every 27 days and it rotates around a captured earth gravity every 27 days. The end result is we never see the dark side of the moon.

A small AWSA training session explained something else that the Moons rotation is increasing and Earth Rotatation is slowing ever slow slightly so that in a few million or billion years there will be catchup of some sort.

[Nesti]

I've seen something similar in hydraulics, where there are 3 pistons with different surface areas, but connected to a common manifold which slowly increases the pressure until a single piston moves, however;

1. The 1sq inch piston has 10lbs on top of it
2. The 10sq inch piston has 100lbs on top of it
3. The 100sq inch piston has 1000lbs on top of it

If you dial up the pressure, which piston overcomes it's supported weight first. Common sense would say they all act at the same time...not so!

Conservation of energy somehow makes the 1sq inch piston move first.

The locking of smaller mass/energy to larger mass/energy isn't surprising.

I actually miss sequenced hydraulics...hydraulics in general is fascinating.

[michaellxv]

It's tied up with conservation of energy and the way the oceans slosh about on the surface of the earth. With each orbit a small amout of energy is transfered from the earth to the moon.

Since Apollo the distance to the moon has been observed to increase by a cm per year. The earths rotation is subsequently slowing and each day is slightly longer.

Eventually a day on earth will be the same as an orbit of the moon and the moon will only ever see one face of the earth.

[Nesti]

This universe gets more interesting by the day...Does the transfer or energy translate to a change in mass, or does gravitational radiation emit that off???

Got a reference for that?

[michaellxv]

This is a good explanation.

http://en.wikipedia.org/wiki/Orbit_of_the_Moon

[Nesti]

Cheers!

[Kal]

no - the moon does not rotate on it's axis. It rotates on an axis which is 380,000 km away, inside the earths crust.

[bojan]

Hmmm

So, each piston sits in it's own cylinder and everything is connected with manifold to the same pump... and they are not connected otherwise (like on a same crank-shaft ?

The relative load on each piston is 1, 10, 100x.

Intuitively, one would think that the largest piston would start move because the force on it's head is the largest..

If we assume there is not friction between pistons and cylinders, all the pistons should start to move simultaneously...

If we take into account the friction, then we have an area between cylinders and pistons which is causing the friction, and the relative sizes of that area is proportional to the product of lengths of the piston (assumed the same for all of them) and circumference of said piston.. which will be proportional to the SQRT of piston head area.

So I think the biggest piston will start to move first, because the relative friction of the widest piston is lowest.


And, yes, the Moon rotates, one rot per ~27 days.
Where that axis is.. it is actually passing through the gravity center of Earth-Moon system.. I think Andrew is spot on here :-)

[adman]

Not really. You get the same effect driving a car around and around a roundabout. Re-occurring and revolving scenery, the car always presents the same side to the centre of the roundabout - but the car is not spinning on its axis. It has forward, but curved motion.

Imagine this - the olympic sport of hammer throw. Big heavy person swinging a ball on the end of a chain. Once it gets up to speed they rotate around their common centre of mass. The ball always presents the same face to the thrower, but it is not spinning on its axis. A tiny observer sitting on the ball's surface would get revolving/re-occurring scenery.

[Nesti]

All pistons would require 10psi to get their respective loads to move. Negate the friction from the seals and the pistons should move at the same time, but apparently they don't.

[michaellxv]

The smaller piston has less mass and is therefore easier to move.

[michaellxv]

In this example the ball and person are physically linked, the moon and earth are not.

Take a view from space above the moon such that the earth was out of your field of view. You would observe the moon rotating on its axis. It's difficult to visualise from our earth bound reference point.

[Allan_L]

Hmmm!
Interesting hypothesis.
I must admit this is the first time I have heard this, but it sounds like a valid explantion of the observed facts.

I will ponder on this for a while. :thanx:

[mithrandir]

The moon rotates on its axis. It revolves around the earth-moon barycenter.

The earth rotates on its axis. It revolves around the earth-moon barycenter.

A bit more accurately, they revolve around the sun-earth-moon barycenter.

Although it you really wanted to be pedantic, you would have to take into consideration the perturbations caused by every other object in the universe.

[Allan_L]

I agree with Adman.

And I propose that the Earth and Moon are physically linked, by gravatational forces.

And I like the comparison to the car on the roundabout too. And they are not even linked. (physically as you put it) Or would someone like to say that the car is revoving on it axis too ?:question:

[bloodhound31]

Exactly! The moon is spinning on it's axis, but I agree that it's axis is not on the moon at all, but near or inside the Earth.

Regardless, it IS spinning as well as traveling a circular orbit.

I love these conversations!:P:D:thumbsup:

Baz.

[bojan]

No they don't because of the friction, the net force is lowest for the biggest piston.

If there is no friction, all pistons start to move at the same time (of course, the biggest will move slower, but this is not the issue here).

[Steffen]

That is correct. The translational and rotational movements are independent from each other. They are superimposed. The Moon spins and has a both an angular and a linear momentum. It would preserve this momentum if the Earth disappeared in a puff of smoke by moving along on a straight line (a solar orbit really) while spinning at rate of 1/27d.

Cheers
Steffen.

[michaellxv]

"The lunar orbit plane is inclined to the ecliptic by 5.1°, whereas the Moon's spin axis is inclined by only 1.5°" http://en.wikipedia.org/wiki/Orbit_of_the_Moon

[bojan]

I think this is irrelevant.. where the axis is.

The important thing is, Moon has rotational momentum.

If Earth, by some miraculous reason disappeared, the Moon would continue to rotate with the same rate (1 rev per 27 days).
And it would continue to orbit the Sun, of course..

[adman]

How can an object spin on an axis that is outside of itself?? Surely that is just called an orbit? The point that it orbits around is the centre of mass of the moon and the earth. Can someone explain to me how it 'spins' around this 'axis' also?

Have a look at these links....

http://www.grantchronicles.com/astro29.htm
http://www.digipro.com/Trials/moon.html

[Nesti]

Because it's not a conventional spin or a conventional axis.

[Kal]

I'm not so sure this is true. If the earth/moon are tidally locked in a rotation then if the earth was removed there would be no object to provide the centripetal force. The moon would in effect stop it's 27 day rotation.

(unless my analogy of swinging an object on a rope and letting go of the rope is wrong?)

[adman]

that's right it's an orbit...!:)

[adman]

Seroiusly though....what do you mean by that?

[Kal]

I was being a bit cheeky with my answer ;) The OP asked if the moon spins on it's axis, which it doesn't, it of course orbits the earth and is tidally locked, which is why I said it spins on an axis inside the earths crust (which is another way of saying a tidally locked orbit) :P

[adman]

I think the analogy of the hammer-throw is a pretty close approximation of the earth moon setup - apart from the fact that the earth is still rotating...

[mswhin63]

Does this all mean that the earrth does not rotate but is tidally lock to the sun.

[adman]

What about an artificial satellite? Say the space shuttle. As it orbits, let's say it keeps it's underbelly oriented towards the earth - an identical situation to the moon,always keeping one face pointing to the earth. Do we say that it is rotating as it orbits the earth, or is it simply flying a curved path?

[multiweb]

:nerd: This whole thread is starting to make my head spin :lol: . Moon's tidally locked to earth so it appears to face always the same way but for libration which I understand is due to the slightly excentric orbit. When you talk about motion or rotation you have to say in reference to what. I reckon the shape of the "orbit of the moon around the sun is something like a flower out of the 70s... without the rainbows :cool3: That's spinning ... or trippin' :question:

[michaellxv]

Yes, my head is spinning. Yes it's a rather pedantic question and debate. But I do find it interesting. Don't know what that makes me :P

[bojan]

Guys,
You have to understand that we are dealing here with complex movement, consisting of two components:
1) orbital component (29days)
2) rotational component (27 days)
Combine them together, and you have moon facing earth always with the same side.

So I aplologise for my erlier comment on axis passing through the barycentre odf the system Earth-Moon, it is not correct, sorry.

[michaellxv]

That one is even harder to visualise as the space shuttle (and other sattelites) have engines to correct their orbit as required so it not quite the same. I also keep seeing images in my head of sattelites being deliberatly spun up prior to release into orbit.

If a die was released from the ISS with no spin as such but it would have the receive orbital momentum from the ISS. Assume that is starts with the 6 facing the earth. Would it fall around the earth and keep the 6 facing the earth or would we see the other numbers as it orbited but did not spin.

6
|
v
6-> E <-6
^
|
6

or

6
|
v
5-> E <-2
^
|
1

[adman]

I get the concept of something having rotational and translational components to its movement - i just don't think the moon has a rotational one :shrug:

[Nesti]

Well, it's really a composites of motion-isn't it?!

The spin is incorporated in with the revolution.

Relative to our central Sun, the Moon does have a spin, but it can only come as a result of the Moons movement around the Earth; like Parallel Transport in GR which I mentioned earlier. Relative to the Moon, it would appear to have genuine spin.

But wait, there's more! An object in orbit should maintain it's orientation to the central mass, ie, the nose of a space shuttle if pointing toward Earth will remain pointed toward Earth because the geodestic pathway curves around the Earth, and the geodesic runs tangental to the curve. This is the conservation of angular momentum being conserved with the geodesic itself...or Newtons third law conserved with the curvature of spacetime...cool hey?!

[adman]

So you would only see the 6 in the die example in post #43 above?

[Nesti]

ABSOLUTELY, if the 6 side is facing Earth and stable, the 6 face will remain facing the Earth as the ISS and dice travels around the Earth 'unless affected by an external force'. This is the preservation of our laws of motion within the geodesic pathway.

So what does that actually mean???
The dice is actually traveling in uniform motion and in a dead-straight line...which just so happens to curve around the Earth. :rofl:

[mithrandir]

For the 6 to remain facing the earth the die (singular noun) has to be tidally locked, so it is spinning, just like the moon. Once it is spinning it takes no force to keep it spinning.

Eventually earth will become tidally locked with the moon. They will both have the same day length, much longer than the current lunar month.

Tidal friction is slowing earth's rotation. Over the last few billion years it has already locked the moon because it is much smaller. The moon is moving away from earth to maintain the total angular momentum, thus making the lunar month longer.

Tides not only affect the oceans. The land has tidal bulges too, just much smaller because it is much less motile.

[Robh]

It depends on your frame of reference.
In their orbit around the Earth, both the Moon and the die/shuttle will have axial rotation relative to the distant stars. Relative to the Earth they may appear to have no axial rotation. As both Bojan and Steffen indicated, if the Earth were suddenly removed from the equation, the Moon would continue in orbit about the Sun but still have an axial rotation relative to the stars. And so would the die/shuttle.

Regards, Rob

[Nesti]

I don't believe it requires to be Tidally Locked to do so. So long as the Earth is uniformly round and dense around the Equator (and it pretty much is), then the geodesic pathway the die travels will be uniform. Remember, the die is moving in a dead straight line with uniform motion through the geodesic. If the geodesic is curving around the Earth, then the die does not need to spin in order for the 6 to remain facing the Earth. Tidal Lock seems to be a slow acting phenomenon like a dynamic system finding equilibrium, but geodesic pathways are always there and are instantaneous.

[michaellxv]

Gravity between 2 bodies acts as if the masses were points of mass at the centre of gravity. Therefore I don't see how gravity is going to cause either body to necessarily start rotating.

[Steffen]

It doesn't. The gravitational force between Earth and Moon isn't what makes either of them spin around their respective axes.

EDIT I should add, if you abandon the point mass assumption (because it is inaccurate and only an approximation) you will have to acknowledge the effects of tidal deformation, which results in any kind of rotation the Moon might have had initially to eventually become synchronous. If the mechanics of the Moon's genesis had not given it any kind of rotation (i.e. a pure translational path around Earth) those tidal forces would have induced a spin resulting in synchronous rotation. Hence, since Earth and Moon are not point masses you can say that gravitation (via tidal forces) can indeed induce rotation (at least in the smaller one of the two).

Cheers
Steffen.

[mswhin63]

As the moon is calculated at a rotation speed of 16.7km/hr suggests it rotates in simple terms, irrespective of tidal forces that are causing it.

http://www.newton.dep.anl.gov/askasci/ast99/ast99142.htm

It is still rotating on an axis.

[mithrandir]

If the die is not rotating once per orbit, it can not always show the 6 face to all observers on the ground.

Suppose the die was not rotating, so one of the faces always pointed at say SXDF-XCLJ0218-0510 - the most distant known galaxy as at May 10 2010. From earth it would appear to be tumbling.

[Nesti]

This is precisely why I said earlier that this is a composite of motions. There is a spin, but it is an apparent spin. This is actually a 'Parallel Transfer' of a body, within a geodesic, around a central mass; like a race track within a gravitational field where the outer wheels must cover a greater distance than the inside wheels; there is a consequence. The Moons spin comes as a direct relationship between it's orbital velocity and the field. The Tidal Lock is probably a feature of how the two fields (Moon and Earth) interact together.

The spin of the Die is attributed to it's orbit around the Earth, but the reason why the Die will always face the Earth (if positioned that way and left untouched) comes down to General Relativity...you see the space and time in which the Die is positioned within the geodesic pathway contains conservation of angular momentum (all laws actually) BUT, the geodesic is a curved path around the Earth, so the space spins around the Earth, not the Die (the space is bent to conform with the filed curvature)...this also means that the 6 face is being compressed and the outside face (opposite to the 6) is being stretched...the gravitational field is trying to turn it into a pie wedge. As the Die orbits the Earth the space which it occupies is rotated in sync with the curvature, so the Die isn't spinning, the space and time which the Die occupies is being warped, the net affect being tidal forces acting upon the Die and a change to the Die's orientation without any effort at all. This is also why satellite moons get crushed in orbit around gas giants to form rings of dust.

A Tidal Lock seems to be both a conservation tendency and a warping issue.

So is the Moon spinning???
I believe it has an apparent spin, but it is also stationary within the gravitational field.

[Steffen]

I think the Moon's rotation and the tidal lock can be entirely explained using conventional mechanics. No need to make the time spin ;)

Cheers
Steffen.

[Kal]

This is a really good answer - helped my understanding and perspective :thumbsup:

[sjastro]

If the die is on a geodesic path it is not subjected to tidal forces.
What actually happens is that the Earth's rotation causes the die to deviate from it's geodesic path (the Lense-Thirring effect). This subjects the die to an external force resulting in the orbital plane of the die to tilt in the same direction as the rotation of the Earth.

This however has nothing to do with the topic.
The fact is the moon spins on it's axis. Tidal locking results in transferring some of the Earth's rotational energy to the moon. This has caused the moon's axial spin period to be equivalent to it's period of rotation around the Earth.

Regards

Steven

[adman]

This to me is the most satisfying answer so far.

[Nesti]

That doesn't make sense Steven. What you are saying is that a moon like Io is being shifted from it's geodesic path which creates the tidal forces rather than Io's spin subjecting Io to changing tidal forces across it's regions. If Io were locked like our moon there would be no volcanic activity as the tidal effects would be static, and that's because the regions of Io would be with respect to Jupiters field. But Io must spin because the tidal forces act around Io are squeezing it at different rates (harder closer to Jupiter), and thus creates internal heating, like heating up a squash ball. Tidal forces are present because a spinning body traveling within the geodesic will have matter which oscilates toward the field centre and then back out within a band which is the diameter of the object that is spinning. So a single point of the surface of the object would take a path much like a nail in a car tire if tracked from a stationary observer on the side of the road, It oscilates between the road surface and the tire height and travels but the band travels in a straight line...but the Die has an overall curvature (around the Earth) because it's in orbit.

Tidal forces would still be acting upon the Die regardless of whether it is spinning or not, but the effects of the tidal forces only become apparent when an object spins because the tidal forces then get to act upon different regions of an orbiting body, like energy from the Sun creates the weather because the Sun's energy gets distributed around the Earth's surface and energy like to migrate to lower regions (ignoring seasons).

The only other way would be if the orbiting body had an elliptical path, where the distance from the field centre varied...where an orbiting body would experience greater field curvature closer to Earth and less curvature farther away from Earth...this too should create internal heating as the tidal forces are changing, even if an elliptic Moon was Tidal Locked, it would still heat up because the field curvature would be more pronounced closer to the Earth.

I agree that Tidal Locking is separate to the geodesic, but the 6 face of the die would be kept facing Earth if the die is undisturbed in the geodesic...in orbit. Tidal Locking seems only to be an energy transfer within the field, like regions of higher energy must flow to regions of lower energy, and thus creates a connection between two parts of the system (like what I said about thermodynamically coupled parts...they are coupled because energy is transferring from regions of higher energy flowing to regions of lower energy); the transfer IS the coupling.

[adman]

in my own mind I waver between thinking that it is a completely semantic argument based around what you define as spin, and being adamant that there is no spin....:P

[Steffen]

You can of course postulate that the universe spins around Moon's axis. But in the sense of classical mechanics the Moon spins around its axis and has a rotational momentum that it will preserve if whatever force made it spin in the first place goes away.

Cheers
Steffen.

[sjastro]

I'm not saying that at all.
Only point masses on geodesic paths are not subjected to external forces (excluding gravity). Since Io is not a point mass the geodesic "passes" through the centre of the moon and intersects at two points on Io's surface. All other points on Io's surface and interior not being on the geodesic are subjected to tidal forces. The Lense-Thirring effect is negligible compared to this.
Since Io rotates on it's axis the tidal forces act at different points on the moon. No difference of opinion here.



Our moon is tidal locked. This doesn't mean that the moon doesn't rotate on it's axis. If Io was tidal locked it would still exhibit volcanic activity for the reasons you have given, because it is still rotating.



You don't need spin for tidal forces to become apparent. Going back to the Io example, if Io didn't spin there would be a more pronounced elongation of the moon. The realignment of this elongated axis to the orbital axis of the Jupiter/Io system due to Jupter's gravity would impart spin on Io. In this case tidal locking would have a very opposite effect.

Regards

Steven

[bloodhound31]

That's gonna make it hard to find the axis of the moon.....first you will have to find the axis of your head....:P

[Nesti]

Oh thank God for that!



I’m not saying that the Moon must not rotate, because it does…I’ve been saying it spins all along. I have also been saying that it is not the intuitive type of spin we are accustomed to.

Sorry, I didn’t say, and should have said that if Io was to show Jupiter only one side (like our moon). That confused the point.



Yes, I know, I did mention that point when talking about the Die. I wrote “this also means that the 6 face is being compressed and the outside face (opposite to the 6) is being stretched...the gravitational field is trying to turn it into a pie wedge”...to clarify that better, the sidea are being squeezed, the back face is being pulled, but the front face is being pulled harder...for our Earth, this translates to a high tide closest to our Moon, low tides on the sides, and a not so high tide on the far side away from the Moon.

Earth
↑
→ ● ←
↓↓




↑↑↑
→ ● ←
↑↑

Moon


Right, I'm off for a lie-down now. :lol:

Cheers
Mark

[sjastro]

Thanks Mark.

The term "tidal locked" is a major point of confusion as it doesn't mean the obvious:).

Regards

Steven

[Nesti]

I don't know what causes it, I'm just assuming it's gravity's version of resonance; maximum amplitude at an optimal frequency for a given body. Or like a ball that always rolls down to the lowest potential...a local minima.

Cheers

[Steffen]

Yes, I'm sure synchronous rotation is the least energetic state for the whole system.

Cheers
Steffen.

[el_draco]

No you could not say this. The leaf would rotate aound the centre of the whirlpool. If it was rotating on its axis, it would spin independently of the whirlpool.

Likewise, the moon "rocks" on its axis whilst orbiting the barycentre of the earth/moon system. The earth rotates on its axis and is not locked to facing the earth/moon system barycentre...

[mithrandir]

It's 35 years since I've done any physics, so any astrophysicist reading can correct me, with explanations.

Any two bodies orbiting each other have tidal bulges. If either one is spinning on its own axis at a speed other than one where both objects always show the same side to each other, the tidal bulges will move on that object. This movement requires/releases energy. The energy has to come from somewhere and the only place it can come from is the individual object's rotation about its axis or the revolution of both objects around the barycentre.

The moon has used up it's store of rotational energy. The moon's tides have locked its face on earth.

The earth is still losing rotational energy to tidal friction and is slowing. Some of this energy is lost as heat. Some is acting to send the moon further away. Eventually earth's face will lock on the moon.

Libration comes from the moon's orbit not being a circle, and the plane of the moon's orbit not being aligned with the plane of earth's orbit. If the moon was not tidally locked we would see the whole surface.

[Astro78]

Just as I was going to reply to the contrary, a picture of the rising earth from the moon comes to mind. It therefore must be in the same 28 day sync as earth

hang on we cannot have the earth rising without any axial rotation from the moon....cancel

edit - there's either wobble in its orbit or it spins on it axis but back and forth and never fully around. Or the pictures were fakes ;)

what a little gem of a Q.

[Nesti]

Sorry but, the ‘Earth Rise’ as seen from the Apollo 8 crew and in photographs were taken in orbit (as with all other Lunar missions). The rise of the Earth came as a result of the motion of the spacecraft around the Moon, not the Moon’s motion. So Apollo 8 witnessed 10 Earth Rises as it did 10 orbits of the Moon.

The Moon does of course have a Sunrise, albeit a very long one. The Apollo missions took advantage of the extended Lunar Sunrises too, the shadows cast across the Lunar surface offered greater depth perception for the crew. As a Lunar day is 29.5 Earth days the shadows barely move throughout the entire descent. Because of the lengthy day, no Apollo crew ever witnessed a Lunar Night while on the surface, and was the reason why they used sun shades during rest periods.

:thumbsup: