Ok I give up. @PeterDonis why say this
You now say this
I explicitly did not equate them at the same time. For the last time I said the expanding Hubble sphere will mean we can see further (than the currently observable Universe) in the future.
The current observable Universe is how far we can see now. That is not how far we will be able to see in the future. Which is what I said. Please point out where I equated the two.
As the Hubble sphere is expanding we will be able to see further in the future. I also know we can see things...
The spectra of the light emitted at the photosphere of the sun , as an example, matches that received at the top of our atmosphere very accurately with small additions from light from the chromosphere and corona.
If there are strong magnetic fields to accelerate free electrons in a plasma then they will emit cyclotron radiation.
Also significant quantities of hot gas (~10% by mass) were missed in galaxies until they were observed in x-rays.
Q1 the spectrum is cut up and stacked. Take the right hand edge of the strip below and attach it to the left hand edge to the one above and so on.
Q2 yes the is normally some signal in the dark bands.
Q3 Yes it remitted but in all directions and not all back to it's original trajectory.
I am not disputing your technical definition but given the baricenter of the Earth Moon system is inside the Earth a Galileo observing from Mars might conclude the moon orbits the earth at least informally. Regards Andrew
You have repeated this several times but I don't understand it. In an Earth centerd model the all solar system bodies orbit the earth in the sense the perform circuits. Yes the are very complex but so is the motion of the moon around the Sun it is not a simple ellipse.
Don't get me wrong I am...
You would still need a reference frame. If you centred it on the earth the Sun would orbit it and vice versa. If you used the fixed stars then yes your right the earth would orbit Sun but the theory is then then stars are fixed. You can't escape motion is relative.
Yes I agree and understand all that, and it is the "obvious choice" but that's still an example of a particular choice motivated by simplicity of the equations of motion i.e. the point I am making. Theory leads to it being the "obvious choice" not raw observation.
Kepler found he could...
I agree but I was trying to reinforce the point I made in post #27. You either need to appeal to "simplicity " or a fixed reference frame ( stars, QSO etc.) to establish a barycentric system.
This is the lesson relativity is it not?
In reality don't you have to make some assumption about a frame of reference for example the fixed stars otherwise you have to appeal to simplicity of explanation. If you don't, you don't have any reason to choose a particular frame.
I don't know the answer to your question but just to observe the zeeman splitting requires and R of 30000 or above. Given the atmosphere I think it would be very difficult with typical amateur equipment.
If I recall correctly they did consider sulphur dioxide as a possibility but dismissed it. You also have to consider the conditions which can broaden the lines, various relative velocities (wind speed, Earth Venus relative velocity) which can shift the lines so it is not as absolute as you might...
Yes wavelength is accurately measured but assignments us a different problem. There are many lines in high resolution spectra and a single line is not reliable proof . Hence the need for confirmation. This is standard practice and does not challenge all of spectroscopy.
Both, on a large scale you can treat the molecular cloud classically. If you want to look at the details of particle interacting then QM might be more accurate although even here classical approximations may be good enough.
In colapse to stars gravity is the driver with em getting rid of...