We could say that the annual parallax of a star is the angle defined by the sun, the star and the Earth. (considering the star perpendicular to the line that unites the Sun and the Earth).
Astronomical aberration is a phenomenon that makes a star, seen in a telescope, appear in a place slightly different from the expected. Aberration has been observed in 1727 by the English astronomer James Bradley who, in the course of his surveys, noticed that stars seemed to be subject to a slight movement within a period of one sidereal year. He thought that this movement depended on the position of the star inside the celestial sphere. Read more
When considering earth as stationary and flat, the sun must be moving on a conic trajectory . (Maybe you can remember my article “Our Earth Pond and the Tent of the Sun”). In the same way the moon, in its movement in the space/ time, has to follow a trajectory moving in the shape of a cone. And this will be the basic theme of the following consideration.
As indicated in the articleThe-paradox-of-gravity-not-respecting-the-energy-conservation-principle/ satellites are subject to a double different force, the gravitational one and the centrifugal one. This implies that the nearer a satellite is orbiting around the earth, the faster it has to move to win the bigger gravitational force and the other way round. To better describe this idea we have to introduce the concept of angular moment. This is the product of the impulse of the satellite ( I=mxv where I is the impulse, m is the mass of the satellite and v its speed) and the distance of the satellite from the Earth, R. Read more
The reproducible reality
Math is the key to understand and describe the universe. The question is: can we consider the opposite situation always true? I mean, is it possible to reproduce in the real world all the ideal abstractions that are possible in the math world? Read more