“Then just lay out the problem, being specific about times, angles and the frame of reference : ) Specifically which time you are talking about, i.e. the time the light is reflected from Pluto or the time your eyes actually see the reflected light, and what your earth based angular references are.” [excerpt]For simplicity, imagine all the planets/sun were stationary, except the earth was rotating 360 degrees per 24 hours.
“If you would read the Feynman reference, you would see that they are all basically the same problem : ) The Feynman reference is a little more complicated of course.” [excerpt]Post a link.
“What is your frame of reference for the 21 arc second discrepancy? I am guessing that you are referring to the earths orbital speed of 30 km/sec to get your 21 arc seconds. If that is the case you are correct, but it should be added the angular component that we are talking about.” [excerpt]Annual aberration(earth's orbit around the sun) is 20.49552 arcseconds, or 0.0056932 degrees.
“It is from the earths rotation of course. We are using the Earth as our frame of reference. If the Earth wasn't rotating the Sun would be stationary, very much like the Earth is stationary to an observer whose frame of reference is the moon. If you were standing on the Moon you would see a stationary, spinning Earth.” [excerpt]Lets say you had a device that had two arrows, one pointing in the direction of the incoming light of the sun, and the other pointing at the gravitation pull of the sun.
“Because we are talking about 'APPARENT' position which is irrelevant to the actual position. At any given time I think I could find two observers on the Earth one of whom could truthfully tell me that the Sun is due East at 90º and the other who could tell me that the Sun is due West at 180º It is a fact, but it is irrelevant to astronomers or anyone else for that matter : ) That is why you don't see it in Wikipedia.” [excerpt]Actually, we are talking about the direction of incoming light from the sun versus the direction of its gravitational pull.
“Slight of hand logic? All you have to do is go outside and pound a stake into the ground pointed at the Sun so that it doesn't have a shadow. Then 8.3 minutes later pound another stake into the ground (with the same origin point) so that it doesn't have a shadow and measure the angle between the two stakes. If you do it accurately enough the two stakes will be a little over two degrees apart. Which is the difference between the apparent position and actual position of the Sun from your perspective on the Earth.” [excerpt]I know what 2.1 degrees looks like.
You still have to have to define the "when".
Post a link.
Buy the books and study them. A little education won't hurt you : )
Annual aberration(earth's orbit around the sun) is 20.49552 arcseconds, or 0.0056932 degrees. Diurnal aberration(earth's rotation around its poles) is 0.32 arcseconds, or 8.88888889 × 10-5 degrees.
So I basically guessed correctly where you got your 21 arc seconds from : )
Lets say you had a device that had two arrows, one pointing in the direction of the incoming light of the sun, and the other pointing at the gravitation pull of the sun. (It doesn't matter how you spin this device, the arrows ALWAYS point DIRECTLY at their respective targets.)
Now lets say its mounted on the north poll. This devices base rotates at the same speed and on the same axis the earth rotates on.
Your asserting that the optical arrow will point 2.1 degrees behind the gravitation arrow. Correct?
No. They would both point towards the actual position of the Sun. Or close enough for Government work anyway : )
Now, lets say you mount this device's base so that it can rotate freely around the earth's axis of ration.
If you were to rotate the base in the opposite direction of the earths rotation at 360° per 24 hours, so that the same side of the base always pointed at the sun, would the optical arrow still lag the gravitation arrow by 2.1°?
That's the same question. The answer is still no. You are basically taking the rotation of the Earth out of the equation, just like an observatory. Granted there are some other factors but they are unimportant for our discussion.
Actually, we are talking about the direction of incoming light from the sun versus the direction of its gravitational pull. You are incorrect.
No what you are missing is that light takes time to reach its destination, the field effects of gravity are instantaneous. The is where the whole discussion started, with field effects : ) You need to get up to speed.
We're not talking about 2 peole on oposite side of the earth.
We are talking about the direction of incoming light versus the direction of gravity.
We are talking about the apparent vs actual position of a person on the equator of the earth with a Sun that appears to rise in the East and set in the West : ) If you change the point of reference the observation changes.
I know what 2.1 degrees looks like. How does that tell you where the gravitational pull is?
All that proves is that the earth turns 2.1 degrees in 8.5 minutes.
First you have to determine the speed of light and the distance of the Sun to the Earth, but if you accept that it takes light 8.3 minutes to get from the Sun to the Earth and that the light is traveling in a straight line the geometry is indisputable. Are you disputing that the light takes apx 8.3 minutes to get from the Sun to the Earth?
It does NOT prove that the angle of incoming light is lagged 2.1 degrees behind the angle of gravitation pull of the sun.
Technically you are correct. It says nothing at all about gravity. For that we will have to get into Field Equations : )
Based on your questions, may I assume that you have conceded the point that for an observer on the Earth (Equator or areas where the rises in the East and falls in the West) That there can be a considerable difference of up to 2.1 degrees between the Suns actual position and apparent position?
No cigar.
Time for some history and astronomy lessons ...(NOTE: The sun is a star)
Starlight and Rain
The next substantial improvement in measuring the speed of light took place in 1728, in England. An astronomer James Bradley, sailing on the Thames with some friends, noticed that the little pennant on top of the mast changed position each time the boat put about, even though the wind was steady. He thought of the boat as the earth in orbit, the wind as starlight coming from some distant star, and reasoned that the apparent direction the starlight was “blowing” in would depend on the way the earth was moving.
Another possible analogy is to imagine the starlight as a steady downpour of rain on a windless day, and to think of yourself as walking around a circular path at a steady pace. The apparent direction of the incoming rain will not be vertically downwards—more will hit your front than your back. In fact, if the rain is falling at, say, 15 mph, and you are walking at 3 mph, to you as observer the rain will be coming down at a slant so that it has a vertical speed of 15 mph, and a horizontal speed towards you of 3 mph. Whether it is slanting down from the north or east or whatever at any given time depends on where you are on the circular path at that moment. Bradley reasoned that the apparent direction of incoming starlight must vary in just this way, but the angular change would be a lot less dramatic. The earth’s speed in orbit is about 18 miles per second, he knew from Römer’s work that light went at about 10,000 times that speed. That meant that the angular variation in apparent incoming direction of starlight was about the magnitude of the small angle in a right-angled triangle with one side 10,000 times longer than the other, about one two-hundredth of a degree.
Notice this would have been just at the limits of Tycho’s measurements, but the advent of the telescope, and general improvements in engineering, meant this small angle was quite accurately measurable by Bradley’s time, and he found the velocity of light to be 185,000 miles per second, with an accuracy of about one percent.
Do you not know that the sunlight is refracted upon entering the atmosphere thus changing the direction of the rays?