<<The Earth Sun distance will change depending on the position of Earth.>>
True.
The Milankovitch Cycles.
orbital migration - The Three Elements in the Milankovitch Cycles - Astronomy Stack Exchange
Those could be regarded as major effects on Climate Change. However, while those Earth Sun distance factors are working, there is another perturbation at work that is effecting the Earth Sun distance. The position of the Major Planets (and to a very minor effect, the smaller planets). It is that variation that Valentina Zharkova is referring too, and whose existence was denied the AGW spokespeople. The fact that Valentina was using JPL data (whose data MUST be very accurate for Space Vehicle calculation purposes) would also be not lost on them. They must have been ordered to do a hatchet job on Valentina's work. There is no other explanation that is plausible to me.
Chaos Theory is precise but as the mathematical equations are non linear they come up with different answers depending on the stating condition, or any small changes. If you have a computer, millions of solutions can be calculated and plotted out to show the "strange attractor" as described in Chaos Theory text books. A good example of really chaotic movement would be the video of the three bodied problem shown earlier.
Perturbation Theory works on the same equations, but makes mathematical approximations of various sorts to come up with reasonably accurate answers. If the "perturbation" prediction is extended the mathematics gets very complex indeed, and you really need to know your mathematical onions as it is easy to make a mistake and come up with a wildly wrong answer. When you have approximately stable orbits of planets around a big central mass like the Sun, perturbation theory works to a large degree of accuracy.
Incidentally I decided to dig up an old port of mine on perturbation theory. Couldn't find it. It was a big subject once upon a time. Still is in a way, buy it has been largely superseded by Chaos Theory and computers.
When I was at college, one whole wing of the library was dedicated to Perturbation Theory. These days a college library would probably only have half a shelf of text books on it I suspect. My guess is the Planet Sun Distances calculated by JPL would take both the best (and most suitable) Perturbation Theory, plus some big computers, and a bunch of software engineers to get the very best data they can, as it would be important for space vehicles and satellites. I am sure they would have similar projects for tracking all the space junk too. And the Asteroids etc. |
