Helping members understand the physics of Space.

Originally posted by jeenyus2008
3)When you look up pictures of a Nebula is that how we would see it (With all the neon colors) or would it not be so glorified? Could we even look directly at one?

You can look directly at nebulae with telescopes (though I would recommend using averted vision, that's a whole different yet related subject), but you generally won't see much color. If it's bright enough it might start to stimulate your green cones as they're the most sensitive, but otherwise you will only see the nebula with your rod cells. Human night vision is color blind.

If your eyes were sensitive enough, or the telescope was massive enough, you would see the colors that a standard color camera shows you with long exposures. Images of nebula are taken in "true" color, but they are also sometimes taken in false color (called narrowband imaging) where each color corresponds to a certain emission line and element of the nebula. It all just depends on how the picture was taken. The latter tends to be more frequently the case with professional images, but amateurs also do narrowband imaging sometimes.

It's an especially handy way of beating light pollution; most light pollution occurs at wavelengths of light outside the emission lines of nebulae, thus by restricting the light that comes in to just those emission lines, you can exclude the light pollution. Here's an image of M16, the eagle nebula, taken in true color:
farm3.staticflickr.com...
Here's the same nebula recorded by narrowband imaging, using the "hubble palette:"
farm5.staticflickr.com...

Originally posted by Illustronic
reply to post by Gordi The Drummer

 

Orbital velocity increases at perihelion and slows when it is farther away at aphelion. This is true with all solar orbital bodies in the solar system regardless of the body's mass. Moons follow the same dynamics orbiting the parent body (the planet they orbit). Rotational speed has no relationship with the proximity a body is to what it orbits, meaning, the spin doesn't slow and speed up at perihelion and aphelion. Tidal friction can slow a rotation over millenniums, as well as eccentricity of an orbit as well as distance of an orbit.

Exactly,
which raises the next question.

How did all those moons fall into such perfect orbit to rotational relationships.

I saw a show in the History channel once that suggested our moon was struck off the earth by a big collision, and since it was once part of earth, that's how it came to be facing the earth so consistantly. I tilted my head to the side and asked myself. "So a big ass comet hit Jupiter 7 times?"


David Grouchy

Originally posted by davidgrouchy

Originally posted by ngchunter

Originally posted by davidgrouchy
And I only mentioned "Tidal Locking" as it is the prevailing version of hand waving done these days, (the reigning theory) and I call B.S.

I have yet to see a rational reason why you call "BS" on a well established fact. In fact, tidal force which induces tidal locking is used to the advantage of satellite operators in order to assist with attitude control. It's called gravity-gradient stabilization. It works.

So Jupiter, a gas giant, has "tidal locking" on 7 of it's moons.

Way to ignore my post.

All while the equator is rotating on it's axis 44 times faster than the Earth.

How would any of jupiters moons have time to get a "lock" ?

Way to prove you don't understand what tidal locking is or how it works. The rotation of the parent planet is irrelevant. It is simply a matter of the force of gravity being felt stronger on the near side of the moon than on the far side. It even works for artificial satellites.

and what "tide" are they locking onto in the absence of clear oceans.

What tide? Oceans have nothing to do with it. We see the effect of tidal force on the oceans, but oceans do not cause the tidal force.

reply to post by davidgrouchy


"How would any of jupiters moons have time to get a "lock" ?
and what "tide" are they locking onto in the absence of clear oceans.
The big red eye?"

How do Oceans on a planetary body effect tidal locking?? Im assuming gravitys natural pull and push..??

Originally posted by ngchunter

Way to ignore my post.

Did I?

Originally posted by ngchunter

Way to prove you don't understand what tidal locking is or how it works. The rotation of the parent planet is irrelevant. It is simply a matter of the force of gravity being felt stronger on the near side of the moon than on the far side. It even works for artificial satellites.

I knew it.
Yeah I've heard all this before.

It goes something like this. The inside of the moon is not evenly distributed in it's mass. The heavier side is drawn toward earth.

Of course the implication of this is that all 44 moons are lopsided on the inside.

And the real question still remains.
How did all this come about again?





Oh, and before I get accused of sidestepping again,

/sarcasm

great, our orbital mechanics rely on a satellite to always face down hill.

/end sarcasm

So if me, a human, designs a satallite and I make one end heavier than the other, I can expect this kind of result.

Then, who designed all these moons?


David Grouchy

Originally posted by ngchunter

What tide? Oceans have nothing to do with it. We see the effect of tidal force on the oceans, but oceans do not cause the tidal force.

Hey, they named the theory.
I can play all the word games I want with it.


David Grouchy

Originally posted by Illustronic
reply to post by Gordi The Drummer

 

Orbital velocity increases at perihelion and slows when it is farther away at aphelion. This is true with all solar orbital bodies in the solar system regardless of the body's mass. Moons follow the same dynamics orbiting the parent body (the planet they orbit). Rotational speed has no relationship with the proximity a body is to what it orbits, meaning, the spin doesn't slow and speed up at perihelion and aphelion. Tidal friction can slow a rotation over millenniums, as well as eccentricity of an orbit as well as distance of an orbit.

edit on 5-1-2012 by Illustronic because: (no reason given)

Thanks Illustronic!
So, is it this variation in Orbital velocity, which allows these satellites (moons) to present (almost) the same face to the object they are orbiting?
GTD

Originally posted by jeenyus2008

How do Oceans on a planetary body effect tidal locking?? Im assuming gravitys natural pull and push..??

It's true.
The mass of the oceans on earth,
as they shift with the tide,
does have a minute effect on the Moon.


David Grouchy

Now for a refreshing pause in the arguments, "A Month On the Moon". Look closely at the 2:00 mark for the shadow of the moon crossing earth in a solar eclipse.

reply to post by davidgrouchy


Now thats just amazing. Our atmosphere has no effect on tidal gravity traveling through it??

reply to post by Illustronic


Illustronic, I am having a hard time answering the question you posted on the first page. When would we see a full moon during the daytime (if possible)..???

Originally posted by jeenyus2008
reply to post by Illustronic

 

Illustronic, I am having a hard time answering the question you posted on the first page. When would we see a full moon during the daytime (if possible)..???

I'm guessing just before and just after a Solar eclipse of the moon?


GTD

Nahhhh! I give up too!

Originally posted by davidgrouchy

Originally posted by ngchunter

Way to ignore my post.

Did I?

Yes, you did.

I knew it.
Yeah I've heard all this before.

It goes something like this. The inside of the moon is not evenly distributed in it's mass. The heavier side is drawn toward earth.

No, that is not what causes tidal locking. You still do not understand how it works, you just pretend like you do.

Of course the implication of this is that all 44 moons are lopsided on the inside.

Wrong. The movement of the tidal bulge will induce rotational braking regardless of whether the moons are "lopsided on the inside" or not.

/sarcasm

great, our orbital mechanics rely on a satellite to always face down hill.

/end sarcasm

Gravity gradient stabilization works.

So if me, a human, designs a satallite and I make one end heavier than the other, I can expect this kind of result.

No, that is not how gravity gradient stabilization works. Or rather, you're deliberately over-simplifying how it works. Weighing down one end is not necessary. The satellite will naturally tend to align its longest axis along the local vertical. Making one end heavier than the other is unnecessary.

Originally posted by davidgrouchy

Originally posted by ngchunter

What tide? Oceans have nothing to do with it. We see the effect of tidal force on the oceans, but oceans do not cause the tidal force.

Hey, they named the theory.
I can play all the word games I want with it.

Wow, quite a revealing quote. Now I understand what you're doing.

Originally posted by ngchunter
Wow, quite a revealing quote. Now I understand what you're doing.

I doubt it.

I'm advocating my thesis.
As stated in my first post.

Isn't it interesting, though, that there are no orbital periods that are commensurate(Math™ ) with any other.
That they are all irrational(Math™ ) when compared to each other.
One would think that by pure chance, at least one orbital body would have a whole number relationship with at least one other orbital body.

But they don't.

The solar system has no common denominator.
What we have is the theory of gravity.

So who is surprised that I'm poking holes in, and not taking seriously a theory I consider antiquated, and nothing more than a patch job.

By draging the discussion into man made satellites,
when it is clear I'm trying to solve cosmogony,
is disingenuous.

Who's pretending here?


David Grouchy

Originally posted by davidgrouchy
So who is surprised that I'm poking holes in, and not taking seriously a theory I consider antiquated, and nothing more than a patch job.

Playing word games is not a good way to be taken seriously. In fact, it's a good way to be dismissed. If you really thought you were "all that" and thought you had a thesis worthy of greater merit than conventional scientific understanding, then you should have acted more appropriately.

By draging the discussion into man made satellites,

Dragging the discussion? It was an elegant proof of the principle (a principle YOU brought into the discussion) which you failed to understand and decided to play "word games" with.

Originally posted by ngchunter

Dragging the discussion? It was an elegant proof of the principle (a principle YOU brought into the discussion) which you failed to understand and decided to play "word games" with.

Sure, sure,
and my cat drives a green car.
What ever.



It was a Simple challenge.
As stated in my original post.

Find a single instance of a commensurate ratio in the solar system between any two bodies.

You can't and you wont.

But somehow 46 moons all know who their Mommy is.

Not all the moons. Oh no. Just some of the moons.

If the trend was so universal as the feeble-man-made-satallite detour tries to assert,
then why aren't all the moons tidaly locked?

/dismissive snort in the face of a puritan.
David Grouchy

[only about 28% of the moons have synchronous orbits]

One last fun fact for jeenyus2008. Triton, the large moon of Neptune, is the only large moon orbiting it's parent in a retrograde orbit, it's orbiting the opposite direction as Neptune's spin direction. Triton. But it is not the only retrograde orbiting moon, Saturn and Jupiter have small moons with all sorts of orbits, in fact Saturn's moons Epimetheus and Janus trade orbits.

Epimetheus and Janus are the fifth and sixth moons in distance from Saturn. Both are phase locked with their parent; one side always faces toward Saturn. This co-orbital condition (also called 1:1 resonance) confused astronomers, who at first could not believe that two moons could share nearly identical orbits without colliding.

Interesting read about the moons of Saturn. Trojan Moons of Saturn.

Trojan moons are a unique feature not found outside the Saturnian system. A Trojan body orbits at either the leading L4 or trailing L5 Lagrange point of a much larger object, such as a large moon or planet. Tethys has two Trojan moons, Telesto (leading) and Calypso (trailing), and Dione also has two, Helene (leading) and Polydeuces (trailing).

S@F for starting a useful thread which I see has degradated into insults.

Before anyone posts what the large star is below the moon towards the right, it is Jupiter.
I'm surprised that hasn't shown up yet in any forums? That is for NE USA.

Originally posted by mugger
S@F for starting a useful thread which I see has degradated into insults.

Excuse the # out of me for doing my own research and sharing my conclusions.
I'll go cancel my internet now.


David Grouchy