Does the star move?

[Actor]

More than 1/2 of the people in a recent survey did not know that the Earth revolves around the Sun.

They're in good company. In A Study In Scarlet Doctor Watson writes about the great detective Sherlock Holmes.

His ignorance was a remarkable as his knowledge... My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the solar system. That any civilized human being in this nineteenth century should not be aware that the earth traveled round the sun appeared to be to me such an extraordinary fact that I could hardly realize it.

"You appear to be astonished," he said, smiling at my expression of surprise. "Now that I do know it I shall do my best to forget it."

"To forget it!"

"You see," he explained, "I consider that at man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones."

"But the Solar System!" I protested.

"What the deuce is it to me?" he interrupted impatiently; "you say that we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or to my work."

 

[Dwig]

...
It's shifted toward the red. That's why it's called the red shift.

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

 

[EhJsNe]

Actually, you did say something like this when you posted about polarizer filters.

oh, so its common knowledge that a polarizing filter rotates so you can adjust the glare.. hmm.. just asked my wife, nope, she didn't know.. asked my son.. nope, he didn't know either.. my buddy down the street who is getting into photography just now, nope.. he didn't know either.. well there's 4 out of 4 that didn't know.. so clearly it's not common knowledge... now lets try this.. lets see if they know the earth rotates... wife: yup.. son: yup, buddy: yup..

my question about the filter may have been common knowledge to someone who OWNS a polarizing filter.. but, to someone who found one in a bag, and has never used one before, nope.. its not..

don't try to be a smart ass unless you have a leg to stand on..

Actually, it's common knowledge among experienced photographers. Alternately, you can keep the polarizer stationary and rotate the camera. (That was a poor joke but the truth is that rotating the camera won't accomplish the goal! You MUST rotate the filter.)

Uhm...hate to be a smartass....but actually...rotating the camera DOES affect the polarization....at least with my CPL it does...gets kinda annoying going from landscape to portrait orientation when shooting with a CPL....

 

[KmH]

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

Well, pretty much right, if you substitute 'our galaxy' for 'the solar system'.

Andromeda and the Milky Way are on a collision course. Andromeda is blue shifted. The only galaxies that can be blue shifted, based on our current understanding of the universe, are in the Local Group of galaxies.

 

[Plato]

oh, so its common knowledge that a polarizing filter rotates so you can adjust the glare.. hmm.. just asked my wife, nope, she didn't know.. asked my son.. nope, he didn't know either.. my buddy down the street who is getting into photography just now, nope.. he didn't know either.. well there's 4 out of 4 that didn't know.. so clearly it's not common knowledge... now lets try this.. lets see if they know the earth rotates... wife: yup.. son: yup, buddy: yup..

my question about the filter may have been common knowledge to someone who OWNS a polarizing filter.. but, to someone who found one in a bag, and has never used one before, nope.. its not..

don't try to be a smart ass unless you have a leg to stand on..

Actually, it's common knowledge among experienced photographers. Alternately, you can keep the polarizer stationary and rotate the camera. (That was a poor joke but the truth is that rotating the camera won't accomplish the goal! You MUST rotate the filter.)

Uhm...hate to be a smartass....but actually...rotating the camera DOES affect the polarization....at least with my CPL it does...gets kinda annoying going from landscape to portrait orientation when shooting with a CPL....

You're correct. The reason being that, when you rotate the camera, you are ALSO rotating the filter. I realized it after my post but didn't get a chance to edit it. In my mind, I was stupidly thinking of rotating the camera while the filter remained stationary.

 

[DScience]

To the OP: How old are you?

 

[Actor]

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

Well, pretty much right, if you substitute 'our galaxy' for 'the solar system'.

Andromeda and the Milky Way are on a collision course. Andromeda is blue shifted. The only galaxies that can be blue shifted, based on our current understanding of the universe, are in the Local Group of galaxies.

I think you are right. Andromeda is blue shifted. But that's hardly common knowledge even among well educated people. I doubt if one person in 1,000 knows that.

(who's doing the moving is unimportant)

Hear! Hear! Absolutely correct!! Theory of Relativity and all that! By Jove!

 

[Dao]

Thanks .. I read about the red shift and the expanding universe long long time ago when I was in high school.. But did not know about the blue shift.

 

[xeddre]

I think you are right. Andromeda is blue shifted. But that's hardly common knowledge even among well educated people. I doubt if one person in 1,000 knows that.

I've spent two years in college as an Applied Physics major yet I only faintly remember the term.

 

[iamacyborg]

Actually, you did say something like this when you posted about polarizer filters.

oh, so its common knowledge that a polarizing filter rotates so you can adjust the glare.. hmm.. just asked my wife, nope, she didn't know.. asked my son.. nope, he didn't know either.. my buddy down the street who is getting into photography just now, nope.. he didn't know either.. well there's 4 out of 4 that didn't know.. so clearly it's not common knowledge... now lets try this.. lets see if they know the earth rotates... wife: yup.. son: yup, buddy: yup..

my question about the filter may have been common knowledge to someone who OWNS a polarizing filter.. but, to someone who found one in a bag, and has never used one before, nope.. its not..

don't try to be a smart ass unless you have a leg to stand on..

To be honest, I was taught about polarizing light when I was doing GCSE physics when I was 15. It doesn't take a massive leap to take what you've learnt in very basic education and apply it to the real world.

 

[KmH]

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

Well, pretty much right, if you substitute 'our galaxy' for 'the solar system'.

Andromeda and the Milky Way are on a collision course. Andromeda is blue shifted. The only galaxies that can be blue shifted, based on our current understanding of the universe, are in the Local Group of galaxies.

I think you are right. Andromeda is blue shifted. But that's hardly common knowledge even among well educated people. I doubt if one person in 1,000 knows that.

(who's doing the moving is unimportant)

Hear! Hear! Absolutely correct!! Theory of Relativity and all that! By Jove!

More's the pity.

The Dopple effect is well known and understood. It works equally well for an approaching and retreating race car or train as it does for galaxies.

I recall the US television quiz show Jeopardy used the Amdromeda example as a Final Jeopardy question. All of the contestants got it wrong by answering 'red shift'.

 

[Phranquey]

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

Well, pretty much right, if you substitute 'our galaxy' for 'the solar system'.

Andromeda and the Milky Way are on a collision course. Andromeda is blue shifted. The only galaxies that can be blue shifted, based on our current understanding of the universe, are in the Local Group of galaxies.

You're partly correct. The Andromeda galaxy is blue shifted because it is moving toward us. Objects moving toward us are blue-shifted, and red-shifted if they are moving away from us....but this applies to any visible object in the universe, not just our local group. This is how Edwin Hubble discovered that the universal is still expanding, and not collapsing in on itself.

 

[iamacyborg]

"moving away from us" is sort of misleading, it's more just a case of us and whatever object moving away from one another, because we don't know which one is doing the moving.

 

[KmH]

There is both "red shift" and "blue shift". Most objects appear to be moving away from the solar system (expanding universe and all that) so red shift is more common. There are objects that appear to be moving toward the solar system (who's doing the moving is unimportant) and are thus blue shifted. I don't know which applies to the relative motion of the solar system and the Andromedia galaxy so I can't say whether red or blue shift is correct in this case.

Well, pretty much right, if you substitute 'our galaxy' for 'the solar system'.

Andromeda and the Milky Way are on a collision course. Andromeda is blue shifted. The only galaxies that can be blue shifted, based on our current understanding of the universe, are in the Local Group of galaxies.

You're partly correct. The Andromeda galaxy is blue shifted because it is moving toward us. Objects moving toward us are blue-shifted, and red-shifted if they are moving away from us....but this applies to any visible object in the universe, not just our local group. This is how Edwin Hubble discovered that the universal is still expanding, and not collapsing in on itself.

The only galaxies (or any other objects) in the universe that can be moving towards us are in the Local Group.

All other galaxies (and other objects) have an overall recessional velocity due to the expansion of the universe.

A galaxy outside the Local Group can display both red and blue shifts from it's rotational velocity. In simple terms 1/2 of the galaxy is going away from us and the other 1/2 is coming towards us. But the overall recessional velocity is still away from us.

Put another way, the rotational velocity just makes the approaching half of the galaxy a bit less red shifted than the receeding half.

 

[Onemarshboy]

he he - awesome!! Take it on the chin mate..... we all have our moments!