Re: The Sky at Night

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I have watched this programme since I was knee-high to the proverbial grasshopper. Do they not have anyone else as knowledgeable as Patrick Moore? As they are still trotting him out at the age of 90.

I have missed the last few occasions it has been on, but I saw the recent one where they were discussing the results of 'Moore's Marathon'. I felt they were making it into more of a comedy show, rather than a serious Astronomy programme.

I also saw a programme recently about the history of the moon presented by a female professor. It was quite interesting, though she was a bit annoying. I cannot believe though that she said that 'the moon spun slowly'

It was obvious she was talking about the length of time it took to ORBIT the Earth, but what a faux pas!

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Ensign MufMember

Originally Posted by Extremely Fluffy Fluffy Thing:

I have watched this programme since I was knee-high to the proverbial grasshopper. Do they not have anyone else as knowledgeable as Patrick Moore? As they are still trotting him out at the age of 90.

It was obvious she was talking about the length of time it took to ORBIT the Earth, but what a faux pas!

Dunno about you Fluffy but I was always amazed at the coincidence of the Moons rotation [day] being exactly the same length as it's orbit of the Earth

I can remember having to do an experiment to prove this one particularly slow day at work in the nineties

6/2/123:10 AM

Extremely Fluffy Fluffy ThingMember VIP10 yearsModerator

Originally Posted by Ensign Muf:

Dunno about you Fluffy but I was always amazed at the coincidence of the Moons rotation [day] being exactly the same length as it's orbit of the Earth

I can remember having to do an experiment to prove this one particularly slow day at work in the nineties

But it doesn't rotate!

That's why, no matter where you are on the planet and no matter at what time of day or night you observe the moon, it is always showing the same face.

(I can see you might be having a bit of a joke. If so I'm not getting it.

Edit to say: After several readings I think I am getting it now.

Must be too early in the day for me!

And my typing's shot to pieces too!

6/2/123:28 AM

Ensign MufMember

Originally Posted by Extremely Fluffy Fluffy Thing:

But it doesn't rotate!

That's why, no matter where you are on the planet and no matter at what time of day or night you observe the moon, it is always showing the same face.

(I can see you might be having a bit of a joke. If so I'm not getting it.

Edit to say: After several readings I think I am getting it now.

Must be too early in the day for me!

And my typing's shot to pieces too!

"How it works: If you go out on several different nights and look at the Moon, you will always see the same features, at about the same position. It looks as if the Moon doesn't rotate! Ah, but it does.

This can be seen using a model. Grab two oranges (or apples, or baseballs, or whatever roughly spherical objects you have handy). Mark one with an "X"; this represents a feature on the Moon. Now put the other one down on a table; this is the Earth. Place the Moon model on the table about 30 centimeters (one foot) away with the X facing the Earth model. Now move the Moon model as if it were orbiting the Earth, taking care to make sure that the X faces the Earth model at all times.

Surprise! You'll see that to keep the X facing the Earth model, you have to rotate the Moon model as it goes around the Earth model. Furthermore, you can see you have to spin it exactly once every orbit to keep the X facing the Earth model. If you don't rotate it, the Moon model will show all of its "sides" to the Earth model as it goes around.

Now, I have been a bit tricky here. We are talking about two different frames of reference; one on the surface of the Earth looking out at the Moon, and one outside the Earth-Moon system looking in. You performed the experiment from the latter frame, and saw the Moon rotating. From the former, however, you can see for yourself the Moon does not rotate. What is being argued here is that in one frame the Moon rotates, in another it does not.

We've actually learned three things:
# 1) the Moon rotates as it orbits the Earth (as seen by an outside observer);
# 2) it rotates one time for every orbit (to that observer); and
# 3) if it didn't rotate, we would eventually see all of the Moon as it orbited the Earth. "
Courtesy of *Bad Astronomy http://www.badastronomy.com/bad/misc/moon_spin.html

Hope this clears it up for you Fluffster

You don't have to use oranges though, simply use your fists and orbit one round the other

6/2/128:17 AM

Extremely Fluffy Fluffy ThingMember VIP10 yearsModerator

Sorry Muf, I see clearly What your demonstration is PRETENDING to demonstrate, but just because an outside body sees different faces of the moon doesn't make the moon have self rotaion. The REAL reason that the outside body is seeing different faces of the moon is because of the ORBIT of the moon round the Earth. The earth orbiting the sun has a secondary effect on the when and how the outside body sees the moon.

6/4/121:49 AM

Ensign MufMember

NASA think it rotates

6/10/126:47 AM

suricatMember

It's a matter of 'perspective' and the point of 'observation' that can cause confusion here IMHO.

Let's take a look at recent 'theory' of how the 'Earth-Moon' configuration came to be about.

It assumes that both a 'Proto-Earth' and a 'close proximity planet' named 'Thea' ('Thea' is assumed to be a [roughly] 'Mars sized planet') came together and impacted one-another '~3.5 b.y.a' (about 3.5 Billion Years Ago) during the formation/stabilisation of our 'Solar System'. Most of the heavier 'debris' from this collision 'fell back to, and was absorbed' by the 'Earth' that we now know. However, some 'heavier components' released by this collision 'escaped' Earth's 'gravity' with 'lighter components' and collected with the 'heavier elements' to 'orbit the Earth' and form a 'firm structure' that we now know as, and call, 'the Moon'. Given that 'lighter elements' were 'flung' into a 'higher orbit', the 'heavier elements' enjoyed a 'lower orbit' due to the energy imparted by the collision. This implies that 'Earth's Moon' may well be 'unbalanced' on the property of it's 'centre of gravity'. Should this be the case, the 'centre of gravity' would impart the greatest attraction to 'the nearest mass/planet. We see this in the activity of the Moon's 'notation'. The Moon 'nods' backwards and forwards from an Earth perspective with an influence from 'the Sun' and 'tidal affectation'.

To me, this displays the property of a 'satellite' that is 'held' by its 'gravitational origin' and 'prevented from rotation' by its 'offset' to a 'central gravitational origin' that is 'normal' for planets.

Kind Regards, Ray Dart, (suricat).

11/8/228:17 PM

suricatMember

'Ensign Muf'. Are you Mr 'Diver'? That would be 'cool'! However, the moon doesn't 'rotate around the Earth In 'almost' 'stationary orbit' around the Earth as its energy. The 'Sun' also .

11/8/229:46 PM

suricatMember

I've re-read this thread and realise that I've probably only increased the confusion for this phenomenon.

Because the Moon is still mostly influenced by Earth's gravity, even though the Moon continues to escape Earth's gravitational influence (is moving away from the Earth) at the rate of the 'growth of a human fingernail', another influence may also be responsible for the Moon's 'notation' (nodding back and forth) other than 'gravitational variance' from Sol and other local mass influences.

Whilst we realise that 'most' planets in our 'Sol' System' 'rotate' in the same direction of rotation, there are some, such as Venus and Uranus that rotate as 'retrograde' and at approx 90 degrees respectively to the general 'system's' rotation. Why?

I would suggest that these planets may have encountered a 'collision' that altered their normal/usual rotation, and here's why I make this suggestion.

A 'steady state' for 'Sol's system' (our Solar System) would require all orbiting planets to comply with the influence of the 'ionic mass ejection' from Sol. This implies that the 'leading edge' (the leading portion of the planet in its orbit) of each planet encounters a 'greater mass' of Solar emission than its 'trailing edge' by vrirtue of its orbital movement. This phenomenon can also provide a valid explanation for the 'nodding phenomenon' of the Moon.

Kind regards, Ray Dart (AKA suricat)

4/29/238:40 PM

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